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WorldWide Telescope - Всемирный телескоп
Руководство Пользователя
Примечание: Этот документ носит предварительный характер и может быть изменен.
Всемирный телескоп является программной средой, которая позволяет компьютеру функционировать как виртуальный телескоп -
совмещая терабайты изображений с известных телескопов Хаббл, Чандра и Спитцер в одну огромную панораму Вселенной.
Всемирный телескоп позволяет бесшовные панорамирование и масштабирование ночного неба, нашей Солнечной системе, и других космически
ориентированных панорам, таких как фотографии, сделанные на поверхности Луны и Марса.
С его помощью можно исследовать звездное небо в разных спектрах, например, в рентгеновском диапазоне, и увидеть яркие радиационные облака,
а затем переключаться на видимый свет и открыь для себя облака, оставшиеся от взрыва сверхновой, случившегося тысячу лет тому назад.
Спектр водорода Alpha позволяет увидеть распределение и сруктуру массивных первичных облаков водорода, освещенных потоком высокой энергии,
идущим из близлежащих звезд в Млечном Пути.
Для большей наглядности, наша Солнечная система моделируется в трех измерениях, с планетами, которые вращается вокруг своей оси и
обращающееся вокруг Солнца. Можно увидеть величественную красоту в кольцах Сатурна или далекую орбиту карликовой планеты - Плутона,
их точно рассчиатанное движение по небу за дни и годы. Можно ускорить движение времени в модели орбит, чтобы спланировать визит в
лучшее место для наблюдения следующего солнечного или лунного затмения.
В начале работы со Всемирным телескопом рекомендуется просмотреть экскурсии (туры) по звездному небу, которые подготовили для вас астрономы и
преподаватели из известных обсерваторий и планетариев. Большинство функций станут понятны по ходу работы с программой.
Это руководство должно помочь понять, что происходит "за экраном", и найти нужную функции из всего разнообразия
возможностей платформы.
Существуют две версии Всемирного телескопа: Windows-приложение и веб-клиент. Этот документ описывает обе версии,
при необходимости уточняя, что функция доступна лишь в одной из них.
Различие состоит в том, что Windows-приложение сначала загружается, затем устанавливается, и, наконец, запускается на компьютере пользователя,
при этом предоставляя больше функций. Веб-клиент не надо скачивать и устанавливать, он работает в веб-браузере по технологии Silverlight™,
имеет меньше возможностей, но может быть адаптирован под задачи пользователя. Обратите внимание на следующие пометки в каждом разделе:
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Зеленый означает, что функция доступна,
желтый, что выполняется частично, и
красный, что она не доступна. |
Всемирный телескоп создан в Microsoft Research с помощью
высоко производительного Microsoft ® Visual Experience Engine™.
Проект посвящается легендарному исследователю Джиму Грею,
без которого он бы не случилося.
Всемирный телескоп является свободно распространяемым ресурсом
в области астрономии и образования в надежде на то, что он будет вдохновлять
и давать людям возможность исследовать и понимать мир как никогда раньше.
Всемирный телескоп находится в стадии разработки в Microsoft Research.
Вы можете связаться с командой разработчиков или оставить комментарии на общественных форумах.
Вы можете частным образом сообщить об ошибке, задать вопрос или оставить комментарий
непосредственно команде разработчиков в Microsoft Research, перейдя по ссылке
WorldWide Telescope Support и выбрав
Issues and Bugs.
Чтобы опубликовать свой комментарий о Всемирном телескопе, вы можете добавить соответствующую запись на
нашем форуме.
См. также
Продвинутые пользователи могут адаптировать веб-клиента Всемирного телескопа под свои задачи согласно
WorldWide Telescope
Web Control Script Reference, а также работать с форматами и файлами данных согласно
WorldWide Telescope
Data Files Reference.
Чтобы посмотреть чертежи и инструкции по сборке небольшого планетария, воспользуйтесь ссылкой
WorldWide Telescope Planetarium.
На следующем рисунке показан первый экран, который появится в начале работы со Всемирным телескопом.
В этом разделе описана общая компонвка экрана телескопа, и как она меняется в зависимости от действий пользователя.
В верхней части экрана в главном меню с элементами Просмотр, Экскурсии,
Поиск, Сообщество, Телескоп, Вид и Параметры.
Эти элементы подробно описаны далее в документации, однако основная цель каждого из них состоит в следующем.
Обратите внимание, что на основные элементы меню можно нажимать мышью, и при этом они ведут себя не так, как при нажатии на
стрелку под ними для выбора из выпадающего списка функций.
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При наведении мыши под главное меню будет отображаться стрелка вниз.
При нажатии на эту стрелку вниз открывает выпадающий список функций для этого элемента меню.
При нажатии на элемент главного меню (например, при нажатии на первую кнопку Просмотр)
изменится внешний вид верхней панели, но не будет показан список функций.
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- Просмотр
: первые два пункта меню, Создать и Открыть,
используются для создания новых или открытия существующие файлы данных, соответственно.
Это основные функции меню Просмотр - расположение данных на дисплее.
Нажатие на саму кнопку Просмотр покажет данные Коллекции
в виле иконок на верхней панели. При выборе любой из этих иконок будет либо
открыт набор изображений, либо выбранное изображение будет отображено в окне просмотра.
Наборы данных и отдельные изображения представлены иконками (по аналогии с папками и файлами).
Наборы изображений в WWT называются коллекциями.
- Экскурсии
: Туры во Всемирном телескопе представляют собой анимированные слайд-шоу из области образования или
научных исследований, которые обычно посвящены определенной теме. Нажатие на кнопку Экскурссии откроет
на верхней панели список Туров, которые поставляются с программой по умолчанию.
Функции выпадающего меню (по стрелке вниз) позволяют поиск туров в сети создание (редактирование)
новых туров. Открыть существющий тур можно также с помощью функции Просмотр > Открыть.
- Поиск
: при нажатии на эту кнопку главного меню в верхней панели будут показаны
параметры поиска данных, которые используются по умолчанию. Для поиска данных в сети
эти параметры можно менять с помощью дополнитьельых функций под стрелкой Поиск.
- Сообщество
: сообщество во Всемирном телескопе - это открытая или закрытая группа пользователей, которая может быть создана
для обмена данными. При нажатии на кнопку Сообщество на верхней панели будет показан список Мои сообщества,
Естественно, при первом нажатии этот список будет пустым. Используйте функцию Вступить в сообщество для перехода
на веб-страницу со списком открытых сообществ. Если вы вступите в одно из них, оно появится в списке Мои сообщества на
верхней панели и откроет вам доступ к новым данным и документам.
- Телескоп
: этот пункт меню позволяет управлять настоящим
телескопом, который может быть подключен к компьютеру с помощью
USB-кабеля и соответствующего программного интерфейса.
Если у вас есть такой телескоп, эта функция открывает интересные возможности,
включая использование Всемирного телескопа для наведения или поиска объектов
в небе, и, возможно, наложения своих собственных изображений на звездную карту
в окне просмотра.
- Вид
: при нажатии на эту кнопку будет на верхней панели будут показаны параметры, которые управляют видом
основного окна просмотра. Например, можно включить режим Stereo для просмотра Анаглифических изображений,
используя специальные очки.
- Параметры
: при гажатии на эту кнопку будет отображаться ряд настроек программы Всемирный телескоп. В выпадающий список настроек
входит функция выбора Языка сообщеий программы (по уиолчанию - английский).
Верхняя панель показана на рисунке ниже. Она представляет собой прозрачное окно, в котором показаные иконки изображений.
При наведении на иконку курсора мыши отображается текст описания данных.
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В этом окне верхней панели, выбранном по иконке Созвездия, показаны иконки 89 созвездий. Астрономы
заметят, что всего созвездий 88, но в программе Виртуальный телескоп созвездие Змеи (Ser) разделено на два. |
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Если не все иконки умещаются в окне верхней панели, то на нем справа вверху будет показано
число рядов в таблице и стрелки вперед и назад.
Используйте стрелки или колесо мыши для прокрутки списка.
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См. также
Под верхней панелью находится основное окно отображения. В данном примере пользователь выбрал на верхней панели
Созвездия затем Кассиопея:
На изображения звездного неба можно наложить границы созвездий. Созвездие в центре окна называется выбранным созвездием,
и его границы веделяются желтым. Красными линиями покзаны фигуры созвездий, которые опираются на звезды согласно графической
традиции. Созвездие Кассиопея (Cas) известно по пяти ярким звездам, которые образуют букву W.
Использую функции в меню Виб и Параметры, можно выбирать отображаемые линии и их цвет.
На рисунке выше показаны линии, которые выбраны в программе по умолчанию.
Навигация в окне просмотра осуществляется в основном с помощью мыши. Используйте колесо мыши для приближения и удаления. Удерживайте левую кнопку
мыши для поворота угла зрания.
По щелчку правой кнопке мыши всплывает прицел Видоискателя, который можно перемещать в окне просмотра
с помощью мыши и наводить на интересующие объекты. На рисунке ниже видоискатель наведен на одну из звезд в созвездии Кассиопеи.
Чтобы убрать курсор, надо нажать на крестик X в правом верхнем углу Видоискателя.
См. также
Под основным окном просмотра расположена нижняя панель. Оно нужно для многих фунций, главными из которых выполняют
элементы Смотреть на и Изображения.
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Список Смотреть на содержит Earth (Земля), Planet (Планета),
Sky (небо), Panorama (панорама), and
Solar System (Солнечная система).
Это самый высокий уровень разделения, на что смотреть.
Выбор Solar System открывает впечатляющий вид на трехмерную модель Солнца и планет солнечной системы(этот возможность
на сегодня не доступна в веб-клиенте). Из списока Изображений можно выбрать один из объектов в разделе
Смотреть на. Для солнечной системы Solar System это будет лишь одна возможность - трехмерная модель.
Для звездного неба Sky число возможных видов определяется числом спектральных диапазонов, в которых ведутся
астрономические наблюдения, в дополнение к видимому нам всем ночному небу. Список диапазонов включает рентгеновский (x-ray), гамма (gamma),
микроволновой (microwave), и т.д. Наиболее часто используется, конечно, видимый, но изучение других длин волн позволяет точнее определить, что
происходит или уже произошло с небесным телом.
Панорама Panorama содержат склейки изображений, полученных с Луны и Марса. Выбирая Earth, вы можете
увидеть на Земле улицы и географические детали.
Выбор пользователя в списках Смотреть на и Изображения определяет другие возможности в нижней панели (напр.
Вид и Параметры),
которые будут детально описаны ниже.
Под выпадающими списками в нижней панели находится контекстный список иконок изображений.
Контекстный поиск возможен при каждом изменении вида основной панели.
Список содержит имконки всех объектов, которые видны на основной панели.
С увеличением изображения основное окно содержит все меньше объектов, что сокращает список контекстного поиска.
Например, для выбор Просмотр, затем Созвездия затем
Corvus контекстный список показана на рисунке ниже:
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Контекстный список содержит много объектов, начиная с планеты Сатурн. Это не только объекты, образующие созвездие Ворон (Crv),
но и все те, что попали в видимую область неба на основной панели. Алгоритм сортировки в списке сначала показывает планеты и
объекты с собственными именами, за ними - объекты, имеющие каталожный номер, например NGC4024. Если список не умещается
в окне нижней панели, что бывает часто, то можно использовать стрелки для листания списка вперед-назад. Обратите внимание,
что контекстный список обновляется только после остановки движения изображения в основном окне, и часто бывает пустым в
момент перемещения основного окна по звездному небу. Можно уменьшить размер контекстного списка с помощью настройки
Контекстный фильтр.
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При этих настройках фильтра в контекстном списке будут показаны только звезды и сверхновые -
без черных зевзд и нейтронных звезд! |
Нижняя панель содержит также следующие элементы:
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Стрелки вверх-вниз позволяют раскрыть и свернуть окно нижней панели.
В окне на правом краю нижней панели виден skyball на котором показана часть звездного неба, видимая в основном окне
программы Всемирный телескоп. Там же показаны текущие координаты - прямое восхождение, склонение и угол обзора в градусах
(60:00:00 в нашем примере).
Чтобы сменить точку зрения, можно перетягивать мышью желтый прямоугольник по небесной сфере. Выбор нового созвездия также меняет
координаты на небесной сфере, переводя созвездие в центр основного окна.
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Прямое восхождение и склонение - экваториальные координаты на набесной сфере. Для новичков, их можно рассматривать как
долготу и широту на сфере, соответственно. Угол обзора, или поле зрения, определяет угловую протяженность видимой области
на сфере. Увеличение (zoom) сужает угол зрения, зачастую до долей градуса.
На этом мы завершаем обзор компоновки экрана. Последующии разделы посвящены детальному разбору отдельных функций
платформы Всемирный телескоп.
См. также
Программа WorldWide Telescope должна помочь вам в изучении Вселенной. В этом разделе представлены возможности просмотра, которые она предоставляет иссплодвателем.
Можно выделить пять основных объектов ииследования, которые выбирются из выпадающего списка в нихней панели - Смотреть на :
См. также
Вид нашей планеты из космоса
| Это изображение Гавайских островов получено по данным Virtual Earth Hybrid : |
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Исследуя Землю, можно приближаться к ней и удаляться он нее с помощью колеса мыши, и вращать ее, перетягивая левой кнопкой.
Наклонять и вращать область просмотра можно, перетянивая мышь с удержанием клавиши Ctrl.
Изменяя наклон и выбрав опцию Рельеф в окне Земля и планеты в меню параметров в верхнем окне, можно облететь
Землю с высоты "птичьего полета" и увидеть горняе кряжи и долины в пространственном восприятии.
Используйте меню Вид > Исходное положение камеры чтобы восстановить исходное положение камеры и ее настройки.
В программе WWT доступны несколько типов Изображений
Земли, включая космоснимки, дороги и улицы, ночные огни. |
См. также
See Also
В программе WWT доступны несколько типов изображений Земли, включая космоснимки, дороги и улицы, ночные огни.
Карта стабильных ночных огней Земли лаконична, но она помогает увидеть места, где живут люди. В этом описании мы
покажем, как можно выделить на Земле места с высокими плотностью населения и уровнем дохода, путем сравнения
дневных и ночных снимков.
- В списке Смотреть на выберите Earth (Земля).
- В списке Изображений выберите Virtual Earth Streets (виртуальные улицы).
- Поверните глобус мышью так, чтобы стал виден юго-запад Австралли, затем увеличьте масштаб так, чтобы получилось примерно следующее:
- Не меняя масштаба и наклона, выберите в списке доступных Изображений карту ночных огней Earth at Night.
Обратите внимание, что при изменения типа изображения, его проекция не изменяется.
Теперь смените тип Изображения снова на виртуальные улицы, затем снова переключитесь на карту ночных огней.
Плотность населения проявляется со светом искусственных ночных огней. Яркие области на карте огней точно совпадают с
городами Perth и Adelaide, помеченными на карте улиц.
- Сравните подобным образом другие населенные области самостоятельно.
См. также
Рассмотрим подробнее другие планеты и некоторые луны Солнечной системы.
| Некоторые луны доступны для просмотра при выборе типа изображений Planet (Планеты),
например Ио, одна из наиболее изученных 63 лун планеты Юпитер: |
 |
Рассматривая планеты и луны, пользуйтесь колесом мыши для изменения масштаба, и вращайте объект, перетягивая его мышью.
Для наклона или поворота поля зрания, удерживайте клавишу Ctrl одновременно с перетягиванием мышью.
Изменяя наклон и выбрав опцию Рельеф в окне Земля и планеты в меню параметров в верхнем окне,
можно облететь планеты с высоты "птичьего полета" и увидеть горняе кряжи и долины в пространственном восприятии. На сегодня данные по рельефу
доступны не для всех планет. Наиболее подробно изучен рельеф Марса.
Используйте меню Вид > Исходное положение камеры чтобы восстановить исходное положение камеры и ее настройки.
|
See Also
Olympus Mons is the tallest mountain on Mars (and indeed the Solar
System). At a colossal 17 miles high it is three times higher than
Everest. The following tutorial locates the mountain:
- In the Look At list ensure that Planet has been selected.
- In the Imagery list click on Mars.
- Click Settings and ensure Show Elevation Model is checked.
- Pan and rotate the view in order to locate the mountain -- noting that it is
close to the Martian equator. The mountain can be located visually either from
its top-down view, which is distinctive, or from its proximity to three smaller mountains than are in
a near perfect line. These two views are shown in the following images:
- Zoom in and use the Ctrl key with the mouse to tilt the view to see
just how tall Olympus Mons actually is:
- Olympus Mons is a shield volcano, approximately 340 miles wide. The most recent volcanic activity is
estimated at 2 million years ago, so it is difficult to classify the volcano as extinct. One theory for the huge size
of the mountain is that Mars does not have tectonic plates, so there is no gradual crust movement to recycle the surface.
However this theory is countered by the three mountains in a line, which
suggests a plate edge. The three smaller mountains are also volcanoes and are
named Arsia Mons , Pavonis Mons and Ascraeus Mons, though they are
smaller only in relation to Olympus Mons (Arsia Mons - the southernmost - is the
tallest at about 12 miles high, Pavonis Mons - the middle of the three - the
shortest at 8.6 miles, and Ascraeus Mons - the northernmost - is about 11 miles
high).
- Other surface features of Mars to look for include the great canyon, Valles
Marineris, which runs along the equator and is over 2500 miles long. It is the
deepest known crevice in the Solar System. Mars is also known for its plains,
polar caps, and clear signs of water and wind erosion. Mars surface temperature
is quite cold, ranging from -140 to 20 Celsius. Its atmosphere is mostly carbon
dioxide, but there is enough water vapor to form the occasional clouds.
See Also
Highly detailed surface images and elevation data are currently only
available for the Earth, our Moon, and Mars. However, there is enough
detail
on many of the solar system planets and moons to locate their most
notable features.
- Mercury
| Mercury is known for its craters and ridges,
volcanoes and lava flows. The largest features are the very wide
craters. One of these, the Caloris Basin (30.5 Lat 170.2 Lng) is
particularly interesting because of the so called Chaotic
terrain
that exists diametrically opposite to it (-30.5 Lat -9.8 Lng). There is
a very thin atmosphere consisting largely of sodium. Surface
temperatures range from −183 (at night and in the deepest craters)
to 427 Celsius (when the Sun is directly overhead). | No moons |
- Venus
Venus comes closer to the Earth than any
other planet in size, and closest to the Earth in distance. Its surface
includes mountains, volcanoes, rift valleys, and two continents of
higher elevation than the rest. It's surface is however extremely hot --
around 435 Celsius -- and is partly obscured by clouds of sulfuric acid.
There is no evidence of water erosion on the planet, though there is
small amounts of water vapor in the atmosphere.
Notice that Venus
has fewer craters than Mercury, Mars or our Moon, which suggests the
planet surface is relatively young (about 1 billion years old), though
the dense atmosphere may also protect the surface to a degree. | No moons |
- Earth
| Refer to Earth. |
Our solitary moon is old and heavily cratered, one of the best known
craters is called Copernicus. It can be located visually using the Explore >
Collections > Planets/Moons data (noting the three
craters in a near line), or from its latitude and longitude:
 |
- Mars
| See the description in the Locating Olympus Mons tutorial.
| Mars has two moons, Phobos and Deimos. Some image
data is available, find the thumbnails in the Explore >
Collections > Planets/Moons data. Currently they are not
represented in the Sky or SolarSystem
views. Deimos is notable for its smooth surface:
|
- Jupiter
Jupiter's surface is gaseous so
there are no mountains or valleys to speak of. The most
prominent surface features are the banding and the spots --
with the Great Red Spot being the largest of the spots with
a diameter that exceeds that of the Earth. The spots are
swirling clouds of gas, often referred to as storms but are
surprisingly stable, changing little in size in the years
they have been observed. The banding is caused by clouds of
different colors. The darker brown and red bands are called
belts, and the lighter yellow and white bands
called zones.
Jupiter's atmosphere is mostly
hydrogen with some helium, and traces of many other gases. |
Jupiter has four large moons, Io, Europa, Ganymede (the
largest moon of the Solar System) and Callisto. Image data
for all four
exists in the Planet, Sky
and SolarSystem views.
Jupiter has many
other satellites, totaling at least 63, though none of the
others match the size of the four largest. Ganymede has
ancient dark surface matter, and not quite so ancient
lighter surface matter, marked with grooves and ridges:
 |
- Saturn
| Saturn's surface is relatively bland,
consisting mostly of hydrogen and helium gas. It is known for its
high winds, up to 1000 mph, and lightning that is one million times
more powerful than that on Earth. It is the most beautiful planet in
the Solar System because of its spectacular rings, believed to have
been formed by a comet or other object passing too close and being
pulled apart into tiny fragments of ice and dust. The creation and
rotation of the rings cannot be explained solely by gravity, as
there appears to be an electromagnetic interaction between dark
spokes in the rings that rotate almost synchronously with the
magnetosphere of the planet. | Saturn has a large number of
moons, 53 currently have names, though many are small.
Partial
imagery exists in the Explore > Collections > Planets/Moons
data for Mimas, Enceladus, Tethys, Dione, Rhea, and Iapetus, though
Titan is the most interesting as it has an Earth like atmosphere and
a network of rivers and lakes. Mimas is known for its huge impact
crater -- 62 miles in diameter:
|
- Uranus
| Another gas giant, the surface of Uranus
consists of blue-green clouds -- colored by tiny crystals of methane.
Similar to Jupiter and Saturn the atmosphere is mostly hydrogen and
helium. | Uranus has at least 21 satellites. Partial imagery
exists for the largest five -- Ariel, Umbriel, Titania, Oberon and
Miranda -- in the Explore > Collections > Planets/Moons
data.
Miranda has some strange rocky surface features called
ovoids, that have near parallel ridges and canyons. One of these ovoids is
clearly visible in the partial data:
 |
- Neptune
| Neptune is mainly made
up of hydrogen gas with some helium. Its deep blue color
comes from trace methane ice in the atmosphere. Similar to
Jupiter it is known for its surface storms that appear as
dark irregularly shaped spots. | Neptune has at least
13 moons. The largest, Triton, is the coldest known place in
the Solar System, at -235 Celsius it is less that 35 degrees
above Absolute Zero. This is due in part to the reflective
nature of the surface of Triton. No image data currently exists in
WorldWide Telescope for any of the moons. |
- Pluto
| Recently demoted to a dwarf
planet, Pluto is actually a binary system, rotating in
synchronous orbit with one of its moons -- Charon -- with the center of
rotation being outside of either body's mass. Pluto is now widely
considered to be the largest member of the Kuiper Belt -- a region
just to the outside of the Solar System containing many smaller
objects. Pluto's surface is largely rock and ice, so is cratered,
and it is also known for its bright South pole. | There are
two known moons in addition to Charon, named Nix and Hydra. None of
the three are currently represented in WorldWide Telescope. |
The following programs have been build using the
WorldWide Telescope
Web Control Script Reference, and enable detailed searching of the surfaces of many planets and moons.
Demo Name | Description | Link |
| WWT Web Client Hi-Def Planet Explorer | Provides
a range of options for exploring the surfaces of our Moon and Mars.
Thousands of surface features, including craters, mountains, valleys,
seas, plains, ridges and depressions, are available to step through,
sort, search and view.
Make sure to select the correct planet or moon in the Look
At and Imagery drop down lists, after starting the
program.
| Run |
| WWT Web Client Distant Planet Explorer |
Provides a range of options for exploring the surfaces of Mercury,
Venus, and the four main moons of Jupiter: IO, Ganymede, Europa and
Callisto. Hundreds of surface features, are available to step through,
sort, search and view.
Make sure to select the correct planet or moon in the Look
At and Imagery drop down lists, after starting the
program.
| Run |
See Also
Explore the celestial sphere, the vast expanse above and around us.
| The Crab Nebula is one of the best known features of the constellation
Taurus. It is a supernova remnant: |
 |
There are lots of options for searching the sky. Use the mouse wheel
to zoom, and the mouse to pan. Hold the Shift key to slow the zoom rate
while zooming.
Use the Ctrl key with the mouse to
rotate the field of view.
By default the Explore >
Collections options are shown in the top panel. Collections
is the term used to describe image data. Clicking on any one of the
thumbnails will either open up more collections, or load the image data.
For example, select Hubble Studies, this will give a
new range of thumbnails, some collections and some image data (noted by
the different images in the top right hand corner of the thumbnail):
These images are detailed individual (or composite) pictures of the
objects, and will be rendered over the background sky image. Note the
down arrow in the lower right of the image -- this can be used to show a
much larger top panel, with many more thumbnails present.
Interesting comparisons can be made by using the cross-fade slider
(located in the lower panel) to compare the image you have loaded with
the Sky Survey.
Note that Collections data almost exclusively applies to the Sky
view, and selection one of the Collections options will usually switch
from a Planet, Solar System or
Panorama view, to the Sky.
Now to the
lower panel, and the context list that is generated each time the view
is changed.
A single click in a context thumbnail
(shown in the lower panel) will smoothly scroll to that location. Double
clicking will skip straight to the location, NGC2555 in the example
below. Hovering the mouse over the thumbnail will illuminate the object
with an annotation in the main view (if it is actually visible).
If
there are too many context thumbnails to scroll though, use the up arrow
to show many more of them:
Click in the globe, then drag the
mouse, to change the field of view relative to the Celestial Sphere.
Click in the constellation box to center the view on that constellation
-- Draco in this example:
All of the The View Menu options apply to the Sky view, except the
3d Solar System pane.
In particular refer to the Observing Location pane to select a different viewpoint on Earth.
Also check the Constellation Lines and Experience options in the The Settings Menu.
Use View > Reset Camera to restore a default view
and settings. |
See Also
See Also
A conjunction occurs when two or more objects in the sky appear
close to each other. The following tutorial tracks a conjunction
between the crescent Moon, Jupiter and Venus that occurred on 1st
December 2008.
- In the Look At list ensure that Sky is selected.
- In the Imagery list change the entry to Black Sky Background.
- In the View panel click Setup in the Observing Location panel, and
change the location to Sydney, Australia.
Select View from this location.
- In the View panel Observing Time panel -- set the date to
2008 December 1st,
and set the time to 0 0 0 local time (midnight), or 8 0 0 UTC. Click
OK.
- Select Explore > Constellations and scroll to locate and click on the constellation Sagittarius.
- Zoom in a bit on the Moon, which is right in the center of Sagittarius.
- View the crescent Moon in
a smiley face with Venus and Jupiter.
Note that to show both annotations the following image is a composite of two screenshots.
Conjunctions are a visually interesting phenomenon that usually involve near-Earth objects. To examine a range of distant
features of the known universe, try the following tutorial, or select the examples in the Context Search table.
See Also
In this tutorial the search features of WorldWide Telescope are used to locate our stellar neighbors.
- In the Look At list ensure that Sky is selected, and in the Imagery list
select the Hipparcos Catalog.
- Outside of the Solar System, the nearest known star to Earth is so
dim it is impossible to see with the naked eye. The
star, Proxima Centauri, is about 4.2 light years distant. It has two
very bright neighbors known either as Alpha Centauri (A and B) or Rigil
Kentaurus. To
locate these click on Search so that the search panel appears, and type
Prox into the search text box. Note that the search narrows as you enter
each letter, and it is only necessary to enter a few to locate this star. Double click on the thumbnail to jump to the location.
 | The image shows that there can be some discrepancy between the
recorded position of a star, and its location on a photograph.
Proxima Centauri has an apparent magnitude of around 11.05. This is on a Stellar Brightness
logarithmic scale where the higher the numbers, the lower the
brightness. A value of 11 is 2.5 times dimmer than a value of 10, which
is 2.5 times dimmer than a value of 9, and so on. |
- Use the mouse wheel to zoom out from Proxima Centauri till the
bright stars of Alpha Centuari and Hadar appear (Hadar is also known as
Beta
Centauri). Notice that Proxima Centauri is no longer visible. Hadar has
a brightness magnitude of 0.61 (Rigil Kentaurus is even brighter at
-0.01) and Proxima Centauri has a brightness magnitude of 11.05, which
makes Hadar 15000 times more bright than Proxima Centauri. Our nearest
star is certainly not the brightest!
- To visit the brightest star type Sirius into the search
text box, and click on the thumbnail. Aside from the Sun, Sirius is the
brightest star in the sky by a considerable margin.
 |
Sirius has a brightness magnitude of -1.46. The second brightest star,
Canopus, has a magnitude of -0.72. This makes Sirius very nearly twice
as bright as Canopus.
However, Canopus is 308 light years distant from us, and Sirius
only 8.6 light years, so Canopus would appear much brighter if it was
not so distant.
|
- Another interesting nearby star is Epsilon Eridani. At a distance of 10.5
light years, and with an apparent magnitude of 3.73, it is often visible to the
naked eye. Early observations of the star suggested, but did not confirm, that
it is the nearest star with a planet - a gas giant similar to but larger than
Jupiter - in a 7 Earth-year orbit.
Search on Epsilon Eridani to locate the star. Measurements
using the Hubble Space Telescope have since confirmed the planet's existence.
Planets are very difficult to detect, they are lost in the glare of their parent
star, and their presence is usually inferred from a wobble in the star's
movement (suggesting a nearby gravitational tug), or by coincidence when the
planet crosses in front of the star from our viewpoint and alters the star's
brightness to a degree. Because of these limitations in detection, most of the
nearly 400 planets so far located are Jupiter like in size. The nearest
Earth-like planet so far detected orbits the red-dwarf star Gliese 581 - located
20 light years from Earth. Good images of planets are going to be very hard to
come by.
- Visiting the nearest galaxy requires some definition. Large
galaxies like the Milky Way have many smaller satellite galaxies,
usually called dwarf
galaxies. The nearest known dwarf galaxy is Canis Major Dwarf, about
25,000 light years distant from us. WorldWide Telescope does not yet
have a single image of this galaxy, so we will visit instead the
previous contender for the closest satellite galaxy, the Sagittarius
Dwarf Elliptical Galaxy, believed to be around 70,000 light years from
here. Change the Imagery selection from
Hipparcos to the Digitized Sky Survey and type Sagittarius Dwarf into the search text box.
 |
The Sagittarius Dwarf Elliptical Galaxy is very faint as it currently
resides on the opposite side of the galactic core of the Milky Way. It
is set to pass through the Milky Way and will probably be absorbed
entirely into the larger galaxy.
|
- There are at least 10 other satellite galaxies of the Milky Way.
Some uncertainly exists over the Large Magellanic Cloud galaxy and its
sibling, the
Small Magellanic Cloud galaxy. Initial theories that these two were
satellites of the Milky Way were revised when the speeds of the two
galaxies was calculated to be far to high to be in orbit. Alternative
theories include that these galaxies will pass by the Milky Way, or
that they will not escape
the huge gravitational forces of the Milky Way, and will become
satellites. Typing in Large into the search text box is enough to bring up a
range of thumbnails.
 |
Zoom in on the Star Forming Region in the Large Magellanic Cloud. Sometimes classified as irregular, this galaxy may have been a barred spiral galaxy before
succumbing to the tidal forces of the gravity of the Milky Way. |
- The galaxy most often quoted as our nearest neighbor is the
Andromeda galaxy. This behemoth of a galaxy contains an estimated one
trillion stars, and
is so bright it is one of the furthest objects (at 2.5 Million light
years) that can be seen from Earth with the naked eye. Despite having
many more stars than the Milky Way it is calculated
to have about the same mass, because of the greater amount of dark
matter in the Milky Way. The two giant galaxies are set to collide in
the distant future (a subject of a guided tour in WorldWide Telescope). The Andromeda galaxy is also well known by its Messier Catalog name, M31. Type M31 into the search
text box.
 |
The Andromeda galaxy is a classic spiral galaxy. It has at least 19
satellite galaxies in orbit, including M32 highlighted in the image,
with M110 - an elliptical galaxy containing millions of stars -
visible above the main body. |
- The Andromeda and Milky Way galaxies are the two biggest galaxies
in a group known as the Local Group. The Local Group has a third big
galaxy,
Triangulum, and over twenty smaller galaxies, not including the many
dwarf galaxies. The whole group is part of the Virgo Supercluster. At
about
3 million light years away, Triangulum is the furthest object that can
be seen with the naked eye. It is sometimes referred to as the Pinwheel
galaxy (though this name is also given to another galaxy, M101), but is
most reliably located by its Messier Catalog number, M33. Note that you
will get different search results for each of these three names, even
though they can refer to the same object! This is because
the search is reliant on the names given to the objects by the creators
of the images.
 |
The Triangulum, M33 or Pinwheel, galaxy may be remote but gravitationally bound to the Andromeda
galaxy.
Andromeda is in the top right of this image, M33 just
inside the boundaries of the constellation Triangulum in the lower
center. |
- An object in the sky can usually be located by searching on its
name, or one of its names, but you can also enter its stellar
co-ordinates (known as right
ascension or RA, and declination, or Dec). These co-ordinates are
similar to longitude and latitude on Earth, though right ascension is
often given in hours, minutes and seconds, though it can be given in
degrees. Declination is almost always in degrees. The RA and Dec of
Triangulum are
RA: 1 hour 33 minutes 50 seconds, and Dec: 30 degrees 39 minutes 36
seconds. Enter these simply as 1 33 50, and 30 39 36 into the RA and Dec boxes
in the search panel. Click Go and you will pan and zoom to the location.
- Triangulum may have a satellite galaxy called the Pisces Dwarf, but searching on
this name will not currently reveal the galaxy. However we can locate it using
its known right ascension and declination values, so enter 1 03 55
for RA and 21 53 06 for Dec, and click Go.
 |
The Pisces Dwarf galaxy appears only as the faint cloud between the
bright stars at the top and bottom of the image.
This galaxy
may be spherical or irregular. The light from the galaxy is
blue-shifted, so it is moving towards the Milky Way. |
- All of the galaxies visited so far are part of the Local Group,
which makes up a small part of the Virgo Supercluster. This
supercluster contains
at least 100 galaxy groups, and has a diameter of around 110 million
light years. There are millions of superclusters in the known Universe.
The
Local Group is an outlying group within the Virgo Supercluster. The
Virgo Cluster forms the heart of the supercluster, and contains up to
2000 galaxies. Locate the center of the Virgo Cluster be entering RA 12 27 00 and Dec 12 43 00 into the search panel. Click
Go to see the last image in this tutorial -- the bright
objects in the image are very bright galaxies.
 |
The elliptical galaxy Messier 87 is one of the brightest galaxies in
the Virgo Cluster, and can be seen in the bottom left hand corner of
the image. The two other very bright objects are galaxies M84 and M86.
Most of the other bright objects in this image have been identified as
galaxies, though a few of the less bright spots remain unidentified. |
- The nearest supercluster to the Virgo Supercluster is the
Hydra-Centaurus Supercluster. It is one of the estimated 10 million
superclusters in the Universe. Superclusters may be the largest
independent structure in nature, though there are theories that
superclusters are subordinate to even more enormous
concepts called walls or sheets, which can be a billion light years in length.
Other theories have the superclusters moving in rivers towards objects
with massive gravitational pull. However, a visit to the Virgo Cluster completes
this tutorial.
Note: the Messier Catalog referenced in this
tutorial can be viewed in full in the Web Client version of WorldWide
Telescope, using the following program.
Demo Name | Description | Link |
| WWT Web Client Messier Catalog |
All 110 objects in this famous catalog can be viewed, displayed as a slide show, sorted and searched.
| Run |
See Also
This tutorial shows how to use WorldWide Telescope to plan an evening's astronomical observing.
- Ensure that the Look at box has been set to Sky,
and that the Imagery is set to Digital Sky Survey.
- Next, make sure the Observing Location and Observing time
are set up to match your viewing location.
- Make sure that the View from this location checkbox is
selected.
-
Next click Search and enter Sun. Click on
the thumbnail for the Sun to track it. Right click on the Sun to bring up
and track the The Finder Scope.
-
Click View to bring back the view panel, and fast forward the observing time
(usually x1000
works well) while tracking the Sun. Faint stars and galaxies are best
seen once the Sun is at least 18 degrees below the horizon. Pause the Observing time when the Sun's
Alt is close to -18:00:00. Use reverse time if you
overshoot! Now write down the observing time.
-
The sky now displayed by WorldWide Telescope is ready to be viewed.
Keep your notebook handy to jot down the altitude and azimuth of any object that
might be visible.
-
Click on Search to bring up the search options again, type Solar
System, but this time click the checkbox Plot Results.
Now pan and zoom around the sky to see if any planets will be in view. The
best time to observe a planet, neglecting weather conditions, is close to
its transit time (when it is at its highest point in the sky).
- The plotted results for the Solar System will include our own moon.
It is a beautiful object to look at and it can be so bright it
dominates the night sky. Click the Moon's thumbnail in the search
results panel. Now you can see if the Moon will be above of below the
horizon, what phase it will be in, and what other objects it will be
near.
- Outside of the Solar System, look for constellations and asterisms:
- Look to the north to find the Big Dipper, stars part of the
constellation Ursa Major. The ladle of the dipper has two stars that
can be used to point to Polaris, the north star. Polaris is very close
to the Earth's rotational axis, so it will be in the northern sky at an
elevation equal to an observer's latitude all day and night. Polaris is
a Cepheid variable star, a star with a pulsating
outer atmosphere, making it slightly brighter and then dimmer depending
mostly on its changing surface area.
- If it is winter in the northern hemisphere, Orion the great
hunter will be climbing through the sky. Easily identifiable by his
belt, the constellations surrounding are also interesting. To the west,
find Taurus the bull with a red giant eye, Aldeberan. This star is just
like the northeastern star of Orion, Betelgeuse. A star further along
in its evolution than the Sun, Betelgeuse is no longer fusing hydrogen
in its core, but fusing helium. Hydrogen is still being fused to
produce energy, but only in a shell surrounding the core. This is not a
very stable method of holding a star up and consequently red giant
stars often pulsate trying to establish a steady equilibrium between
gravity pulling material inward while the force from photons created in
the interior push outward.
- The triangle of stars shown below is sometimes called the winter
triangle: (clockwise from upper left) Procyon, Betelgeuse, and Siris.
Sirius is part of Canis Major, the larger of Orion's hunting dogs. It's
a bright massive star that happens to be relatively close to us, it's
the closest star you can see at night in the northern hemisphere. The
bright star south of Sirius in Canis Major, named Wezen, is in contrast
one of the most distant stars you can see without a telescope (at 1614
light years away). Sirius and Procyon are both the brighter members of
a binary system - they are both in orbit with a white dwarf star, the
collapsed core of a star that was once about the size of our Sun.
 |
- In the summer, three bright stars make up the summer triangle.
Counterclockwise from the left, Deneb, Vega, and Altair. Deneb, is an
amazing star, a blue super giant that appears bright in our skies even
though it is over 1400 light years away. It is the tail of Cygnus the
swan. Vega is one of the brightest stars in our night sky and is part
of the constellation Lyra, a harp. Arab astronomers had Vega being part
of a constellation that was a vulture, making the summer triangle three
birds. Altair is part of the constellation Aguilla, the Eagle. These
three stars straddle the background Milky Way, the disk of our galaxy.
The white cloudy appearance is actually due to many stars and nebulae
so distant we can't separate them. You'll have to be far from a city to
see the Milky Way.
- That completes the Sky Tonight tutorial. Take your notes outside at the
calculated time, and scan the skies!
- If you are in the Southern hemisphere, there is an equally great variety
of objects to look for. The two galaxies, the Large Magellanic Cloud and
Small Magellanic Cloud, may be in view. These galaxies may be satellites of
the Milky Way - or may just be passing through - or may even be attempting
to pass by but in fact will become satellites. Big as the Large Magellanic
Cloud is - it is about one tenth the mass of the Milky Way. These galaxies are fairly close to the bright star Canopus.
- Of special interest are the closest stars to Earth (at 4.3 light years),
the binary system of Alpha Centauri, which might be visible in the
constellation Centaurus. To locate it search on its alternative name: Rigil
Kentaurus.
- One of the best known formations in the southern skies is the Southern
Cross. Use the search options to locate any one of its four stars: Acrux,
Becrux, Gacrux or Decrux. Alternatively select Explore,
then Constellations, then click on the Crux
thumbnail.
The bright star mentioned above, Rigil Kentaurus, along with its nearly-as-bright
neighbor Hadar, are visible at the bottom of this image.
- The globular cluster Omega Centauri contains millions of stars, many as
close as 0.1 light years to each other, and may be the remains of a small
galaxy that collided with the Milky Way. It is about 15800 light years from
Earth, and appears as a single point of light to us. There is evidence of a
black hole at its center. Search for it using its catalog name, NGC5139.
- That completes the Sky Tonight tutorial. Take your notes outside at the
calculated time, and scan the skies!
See Also
In this tutorial WorldWide Telescope is used to demonstrate the
purpose behind some of the most commonly used terms in astronomy.
- Objects in the sky are located using right ascension and
declination, often shortened to RA and Dec.
Right ascension
in space is equivalent to longitude on the Earth. Longitude is an
east-west bearing from the Greenwich Meridian, right ascension is the
east-west bearing
from an equally arbitrary point in space - the point where the Sun
crosses the
celestial equator on the March equinox.
The equinox is chosen because at this point the Earth is neither tilted towards
or away from the Sun, but instead is vertically aligned with the Sun (the
solstices occur when the tilt is at a maximum). The celestial equator is
non other than the Earth's equator projected out into space, and the north and
south celestial poles
are simply our own poles projected out indefinitely. Where the Sun
crosses the celestial equator both right ascension and declination are
zero.
Declination is similar to latitude on Earth, measuring a north-south
bearing. Objects above the celestial equator have a positive
declination, objects
below it a negative declination.
The point where the Sun crosses the celestial equator is known as
The First Point of Aries. To locate it
first click open the View panel and uncheck the boxes for Figures and Boundaries, and check the boxes
for Equatorial Grid and Ecliptic/Orbits. Next open the Search
panel. Enter
0 for RA and 0 for Dec, then
click Go.
 |
The track of the Sun across the sky is known as the ecliptic.
The First Point of Aries should now be in the middle of your view. |
- The right ascension and declination of celestial objects do not change,
unless the position of the objects changes relative to the co-ordinate system -
which of course they do, but very slowly, so slowly that it is only necessary to
revise the co-ordinate system every 50 years. Each time a co-ordinate system is
fixed, it is called an epoch. The current epoch, and
the only one supported in WorldWide Telescope, is the J2000 epoch - namely the
position of the celestial objects and co-ordinate system at Noon on January 1st
in the year 2000, at the Royal Observatory, Greenwich, England. The change to
the J2000 epoch was made in 1984, as the positions of stars can be predicted
accurately in advance of the actual year. There may of course be a change to the
J2050 epoch, perhaps sometime after the year 2025.
- Of course stars and all other objects do appear to move in the sky, as a
result of the rotation and orbit of the Earth. At any one moment the
position of an object in the sky can be referenced by its
azimuth and altitude. Azimuth is
similar to longitude or right ascension, in that it is an east-west bearing
from true north. Altitude is an angle rather than a distance, it is the
angle up or down from the horizon. By convention positive azimuth is to the
east, negative to the west, and positive altitude is up from the horizon.
Unlike right ascension and declination, azimuth and altitude change
continuously. For example, open the Search panel, then
enter Sirius in the search text box. When the bright star
Sirius appears, zoom away from it until the view is from Earth (that is,
minimize the zoom completely). Right click on Sirius in the sky to bring up
the Finder Scope.
 |
Note that the seconds values for the Altitude (Alt) and Azimuth (Az)
of Sirius are changing, even when you look at the star in real time.
In the View > Observing Time pane click the
accelerated time button. The altitude and azimuth will now change quite
quickly.
Altitude and azimuth are very useful values
when aligning a physical telescope from Earth to locate a particular
star or planet. The values though obviously are different for every view
point on Earth, hence the usefulness of right ascension and declination
as a fixed coordinate system. |
- The Magnitude entry on the Finder Scope
refers to the apparent magnitude of the brightness of
Sirius. For a description of what this means refer to the Stellar Brightness section, or work
through the Tutorial: Visiting the Neighbors tutorial.
- The Distance entry on the Finder Scope is
clearly the distance to the object in light years. A light year is an enormous distance. The speed of light in a vacuum is
186,282.397 miles per second (a light second), which works out to just under six
trillion miles per year, approximately 5,878,500,000,000 (186.282.397 x 60 x 60
x 24 x 365.2424) miles. The Sun is about 500 light seconds from Earth, the next
nearest star is 4.2 light years away, or over 24 trillion miles. Occasionally
space telescopes pick up events that help us visualize how sizeable a light year
is in relation to the cosmos. For example, click Explore, then
Hubble Studies, then click Supernova1987A.
This will bring up a range of seven thumbnails. Click on the fifth,
Supernova1987A - 28th November 2003. Now click on
the sixth thumbnail, Supernova1987A - 12th December 2004.
 |
 |
Though not taken exactly one year apart these two supernova images just
might be showing one light year in the increased radius of the
explosion. |
- The light year is the most common unit of measurement in astronomy, but not the only one.
Open the Search
panel, then enter
Neptune into the search text box. Click the thumbnail to show the planet, then right-click on
the planet image itself to bring up the Finder Scope. For
Distance, note that it is set at 29 au
(astronomical units). One astronomical unit is the mean distance from the
Earth to the Sun. This unit of measurement is much smaller than a light
year, and is useful within solar systems. The distance of 29 au to Neptune is the distance
from Earth to Neptune at a specific point in time, the measurement will
slowly vary as the planets orbit.
- The three values below Distance in the Finder
Scope are Rise, Transit
and Set. Due to the Earth's rotation almost all visible
celestial objects will appear to rise in the east and set in the west. By
far the most important rise and set times are obviously those of the Sun.
Because stars can only be seen at night their rising and setting may be
invisible to us, however they follow the same pattern. The transit time is
the time the object crosses the meridian of the observer, so in most cases
will be the highest point of the object in the sky. Transit times can become
problematic if the observer is near the poles, where a celestial object can
appear to pass overhead several times. In order to see an object at its
clearest, Earth observers will often try to time the observation to match
the transit time. Rise, transit and set times are different for every
viewing location on Earth.
In the View panel select the Observing Location (New York
in the example below),
and check View from this location. This will ensure we have
a horizon line (rising and setting are obviously meaningless without one).
Next, in the Search panel text box, enter Moon.
Click on the thumbnail for a close-up view of the moon, then zoom out till
the horizon line is in view. Next, bring up the View panel again, and in the
Observing Time pane, accelerate the time to x1000.
You will notice the moon rise and set fairly rapidly. By carefully pausing or
slowing the simulated time down, you should be able to match the rising and
setting times with those on the Finder Scope.
 |
Moonrise in New York.
Rise, transit and set times are given in local time, not UTC. Notice
that the Observing Time of 21:56:11 is just a
minute after the Rise time in the Finder Scope.
|
- Occasionally, instead of rise, transit and set times you will see the word Circumpolar.
This means that the object will not go below the horizon - so will not
rise or set but will be in view all of the time. This happens when the
object is near one of the celestial poles. For example, go to Observing
Location, and instead of selecting a city simply enter some extreme
co-ordinates (Latitude 80 degrees, Longitude 0 degrees in the image below).
Then search for and locate the Sun. Depending on the time of year and location, the Sun can become circumpolar, as
in the example shown.
 |
Accelerate simulated time to x1000 or x10000
to show that the Sun does not dip below the horizon, but instead casts
an ellipse in the sky. |
- For a near perfect example of circumpolar activity select a
northerly location, and use the search options to find Polaris, then
zoom out. Next accelerate the simulated time rapidly.
Note that the star remains almost stationary in the sky as everything
else rotates. Similarly for the southern skies, select a southern city,
search for
Polaris Australis, and again watch as it stays almost stationary in the
sky. These two stars are examples of pole stars. Although Polaris
is often referred to as the pole star, it is in fact just one of many, which change over time, that hardly move in the sky and act as great
aids to navigation. The main reason why pole stars change over time is due to
the Earth's precession. Precession is the gradual
shift in an object's rotational axis or orbit. Earth's precession is induced by
the gravity of the other planets, causing the Earth to wobble on its axis cyclically over a period of 26000 years. It is
because of precession that the epochs mentioned earlier, such the current J2000,
are required. It is also because of precession that the First Point of Aries,
mentioned in step 2 of this tutorial, is currently in Pisces. When the equinoxes
were first recognized, thousands of years ago, this point did lie in Aries! In
about the year 2600 it will cross into Aquarius.
- When using WorldWide Telescope you will find using right ascension,
declination and the J2000 epoch coordinate system the most useful. There are
other coordinate systems. For example in the Search panel
options for J2000, Azimuth and Altitude, Ecliptic
and Galactic are available. The Ecliptic
coordinate system uses the Sun's ecliptic circle as the celestial equator,
rather than a projection of the Earth's equator. However, change the
coordinate system from J2000 to Galactic.
The galactic coordinate system is based on a line from the Sun to the center
of the Milky Way, with a celestial equator in line with the galactic plane.
The Sun rotates about the center of the Milky Way at a speed of about 220
kilometers per second in an imperfect circle, and one rotation is called a
galactic year. It takes around 230 million
Earth years to complete one galactic year.
Now enter
zero for λ and β, then click Go. You should now be
looking at the center of the Milky Way.
 |
The center of the Milky Way is 25000 light years distant, in Sagittarius, shown
here using the US Naval Observation survey.
The actual center is
not visible at most wavelengths, because of the presence of dust, but is
now
known to be a supermassive black hole. |
- This completes the tutorial on terminology.
See Also
Explore the images sent back by manned and unmanned space vehicles.
| The Apollo 12 landing site panorama provides some close up detail of the moon
surface: |
 |
To explore a panorama use the mouse wheel to zoom in and out, and
click and drag to rotate the view. To rotate the field of view,
use Ctrl along with the mouse movements. Use View > Reset Camera to restore a default view
and settings.
|
See Also
See Also
There is much less expanse to explore in panoramas than in the other viewing options. In most cases rotating the view will
cover most of the content fairly quickly. The following tutorial simply goes through a number of the different panoramas,
showing different presentation styles.
- Ensure that Panorama is selected in the Look At list.
- In the Imagery list select Pathfinder: Many Rovers. As only one Rover was present on this mission to
Mars it is clear this is a composite of many individual images. Note the padded landing of the spacecraft. This was
required because of the rock strewn landscape. The rover, named Sojourner, is only 25 inches long.
- Taking and using panoramic cameras is one of the objectives of unmanned missions. However, discerning detail from a
camera at a low elevation and at a fixed point can be problematic. One method of addressing this is to increase the
contrast by coloring the image. In the Imagery list scroll a good way down to
Opportunity: Endurance South (false color). If you compare this with Opportunity: Endurance South panorama,
without the added color, you should get a good idea about why researchers color images.
- To see another method of highlighting landscape, scroll in the Imagery list to Opportunity: Lyell. Rotate
the view until the large crater is in view, shown in the following image:
- Now load the Opportunity: Lyell (stereo) imagery, and using a pair of red and cyan glasses, pan to the same
location in the stereo view. The escarpment certainly stands out!
- Even though the exploratory spacecraft were equipped with panoramic cameras, unfortunately most panoramas have dark
zones where no image was available. Typically these are looking up and looking down, though some panoramas are only
partial. Try Opportunity: Burns Cliff, shown below. for example.
Note that if you load a panorama and see only black background,
rotate the view as the panorama may only be partial.
- Scroll in Imagery to the Opportunity: Erebus panorama. At first the panorama appears complete, but see
if you can find the missing piece. Note the solar panels that cover the spacecraft:
See Also
Explore the Solar System in three dimensions.
|
Three of the most visited objects in the virtual Universe, the Earth, the
Moon and Saturn. For this particular image planet size is magnified to the
maximum: |
 |
To explore the 3D Solar System use the mouse wheel to zoom in and
out, and click and drag to rotate the sky view. However, basic navigation is
much easier using the lower panel thumbnails as the starting point, as there
are only one star, nine planets, and five moons to choose from!
 To
rotate the Solar System view, use Ctrl along with the mouse movements.
Use the Planet Size slider to increase the size of
the Sun and planets dramatically:
 Refer to the 3d Solar System settings in the
View pane.
Of great interest is the Observing Time
pane, which enables the planets to be set in motion (more rapidly than
in real time) and orbits to be observed, and also, for expert users of
WorldWide Telescope, eclipse times and locations to be identified (see
the Tutorial: Tracking a Solar Eclipse).
The high resolution texture entry in the Earth and Planets
pane applies.
Use the mouse wheel to zoom out from the Solar System to view the Cosmos,
pausing on the way to look at the Milky Way, noted for its two large spiral
arms:
Use View > Reset Camera to restore a default view and
settings.
|
See Also
See Also
A solar eclipse occurs when the Moon passes in front of the Sun, as seen from some locations on Earth. The result
is a spectacular mid-day darkness along a path across the Earth. To view the effect in WorldWide Telescope, go through
the following procedure:
- Research a time and location of a total solar eclipse.
NASA maintains a
website dedicated to this task, as do many other astronomy websites. For
example, in the year 2041 April 30th, starting around 12.00 UTC (Universal time, or Greenwich Mean
Time) there will be a total eclipse tracking across Africa and passing close to Lake Victoria.
- Select SolarSystem for the Look At list.
- Ensure that the Planet Size slider is set exactly on
Actual. The geometry will be incorrect if this is not set
correctly.
- Click on the Earth thumbnail that appears in the lower panel.
- In the Settings panel ensure that the Multi-Res Solar System Bodies item is checked.
- In the View panel ensure that the Lighting
item is checked.
- Also in the View menu change the Observing Time date information to the correct date:
Year 2041 Month 4 Day 30,
as one example.
- Also in the Observing Time panel, change the time to Hrs
12 Min 0 Sec 0 and select UTC.
Click Apply. Close or unpin the Date Time Selection panel.
- Now rotate the Earth with the mouse until central Africa is in view. Zoom in a little to see the shadow of
the Moon more clearly.
- Carefully use the fast forward button (setting it to x100) in the Observing Time
panel to view the shadow as it moves across the continent. It should look
similar to the following image as it passes Lake Victoria (at a time of
12.52.05 UTC):
To see the same eclipse but in the Sky view go through the following
procedure:
- Select Sky in the Look At list.
- In the View panel, select Observing Location > Setup and select the city
Kampala, Uganda.
- Also in the View panel, in the Constellation Lines + Overlays panels, check the Ecliptic/Orbits setting.
- Also in the View panel select Observing Time, and set the date to 2041, April 30th. Set the time to 11.30 UTC.
- Select Explore > Constellations and click on Aries. It is in this constellation that the eclipse occurs.
- Zoom in a little to view the Sun and Moon a bit more closely.
- Accelerate the time to x100 to view the eclipse. You may have to pan the screen a bit to keep the eclipse in view.
Note that lunar eclipses (where the Earth passes in front of the Moon which
turns the Moon's appearance a shade of red) are
not currently implemented in WorldWide Telescope.
See Also
The following keys are alternatives to using the mouse or joystick in any
view, or provide additional functionality:
Key | Effect |
| Page Up (or -) | Zoom out |
| Page Down (or +) | Zoom in |
| Arrow Up | Rotate up |
| Arrow Down | Rotate down |
| Arrow Left | Rotate left |
| Arrow Right | Rotate right |
| Shift + zoom (Page Up/Down) | Zoom slowly |
| Shift + pan (Arrow) | Pan at a constant altitude |
| | |
| | |
| | |
| | |
| | |
| Esc | Pause a tour. |
| F5 | Refresh the view. |
| F11 | Toggle between full screen and windowed mode. |
See Also
As an alternative to using the mouse, a USB wired Xbox controller can be used to navigate the view. Simply plug in the
Xbox controller and appropriate device driver software will be located and installed.
The following table provides the
purpose of the controller buttons:
Button | Purpose |
| Right Trigger | Zoom in. |
| Left Trigger | Zoom out. |
| Left Thumbstick | Pan and scroll. |
| Right Thumbstick | Rotate. |
| Left Bumper | |
| Right Bumper | In Sky view each click will step through the
objects in the context search.
In the 3D Solar System view each click
will step through the planets and moons of the solar system. |
| Directional Pad | |
| Back and Start buttons | |
| A X Y and B buttons | |
Other compatible joystick controllers can also be used. If more than one is
connected though, there may be conflicts, so for best results only one
controller should be connected.
See Also
Clicking on the down arrow below Explore opens up the menu
entries.
|
The New options start a new data collection of images,
or initiate the tour creation process.
The Open
options enable the opening of a tour, a data collection, an image (which
will be placed in the sky if it includes AVM metadata, or simply centered if
there is no such data) and, for astronomers only, a Virtual Observatory Table.
Clicking Show Finder will bring up The Finder Scope.
Clicking Getting Started links to this User Guide,
WorldWide Telescope Home Page links to the website.
|
See Also
Guided Tours are annotated and animated slide-shows, created to demonstrate a feature of WorldWide Telescope (such as the
Welcome tour), galaxies (such as the Sombrero Galaxy tour), or different views and perspectives of the sky and Earth (such as
the Multiple Worlds tour). Feel free at any time to pause a
tour, explore on your own (with multiple information sources for objects at your
fingertips), and rejoin the tour where you left off.
Highly rated tours include Tours > Galaxies > Universal Beauty
-- a tour of spectacular sights in the Universe set to music, created by High
Skies. For a clear explanation of the search for Earth type planets, visit
Tours > Planets > Search for Extra Solar Planets, created by the
Harvard-Smithsonian Center for Astrophysics. Or select Tours > Galaxies > Dust & Us to
join Harvard Astronomer Alyssa Goodman on a journey showing how dust in the
Milky Way Galaxy condenses into stars and planets. Select Tours > Cosmology > Dark Matter at Abell 1689 to take a tour with University of
Chicago Cosmologist Mike Gladders to see a
gravitational lens bending the light from galaxies allowing you to see billions
of years into the past. Looking to the future, our own Milky Way galaxy is expected to collide with the
Andromeda galaxy in a few billion years time, which is explained in the
Tours > Galaxies > Impact with M31 tour, created by Francis Reddy of
Astronomy Magazine. The apparent result of a galactic collision is shown in the
Tours > Galaxies > M82 Cigar Galaxy tour by Robert Hurt of the
Spitzer Space Telescope. Other tours cover nebula, eclipses, black holes, the
Apollo programs, supernova and many other topics.
You can also create your own tours, and share them with friends and colleagues.
See Also
To display the range of tours supplied with WorldWide Telescope, click on
Guided Tours. Thumbnails will appear in the top
pane for many different types of tour. These are folders of tours. Click on one of the folder thumbnails to view the range
of actual tours. If a thumbnail is a direct link to a tour, it will contain a large
T in the top right hand corner. If a thumbnail
is for a folder of tours, it will not contain the T, and by default is an image of a folder.
To play a tour, click the thumbnail:
Alternatively, hover the mouse over the thumbnail so that the tour properties appear, and then press the play arrow:
To pause a tour, click the Escape key. You are then free to explore at will.
When a tour is playing the top and lower panes are hidden. To bring these panes
into view, simply hover the mouse over where they normally appear.
To restart the tour, press the play arrow
in the top left corner of the screen. If the tour is not visible in the top
panel, click the name of the tour in the menu bar to bring it up.
Note the thumbnails in the top panel show the tour stops
(the large M that appears in the first image indicates that this is a master
slide - refer to Creating a Tour for more details).
To cancel a tour, click the X by the tour name in the menu bar:
To close a tour after it has completed, either click the X by the tour name,
or the Close Tour button that appears in the final credits. In order to transmit
your rating of the tour, click on one or more stars. If you enter too many stars
and reconsider your opinion, click the star to the left to reduce the number of
stars. Click Close Tour and this rating will be included in the
average rating
presented to other users.
To navigate the folders of tours click on the thumbnails to open up folders and
tours, and click on the text to step back. For example, clicking
Nebula in the image below will close that folder and go back
to display th e contents of the higher level Tours folder:
Notes
- There are other ways to start a tour. For example from the Explore > Open > Tour... menu, from community data,
and from other data collections that contain tours.
- When a tour is selected, a copy of it is downloaded to your local computer,
and the entry Save Tour As... is added to the
Guided Tours Menu Entries. This tour can
then be played again without internet access, and edited (though be mindful of
copyright and ownership issues).
Playing Tours in Demo Mode
Refer to the Guided Tours Menu Entries section for details on how to play one
or more tours in demo mode (that is, continuously).
See Also
Creating your own tour can be as simple as annotating a few images showing
deep sky objects, or locations on Earth. Or a tour can be as immersive as
combining images with art and music and speech to illustrate and enhance a
complex argument or experience.
Tour Properties Dialog
To create a tour, click Guided Tours > Create a New Tour..., or
Explore > New > Slide-based Tour...,
which has the same effect. The first thing that you will see is the Tour Properties
dialog. Give the new tour a title (with a recommended limit of 35 characters,
otherwise the title will be resized or truncated), and add as many of the properties as you can
now. However these properties can be edited later, and some of the details may
well not be finalized until you have completed the content of the tour.
 |
The information entered into this dialog is for informational purposes for
the users that might run the tour.
The author image should measure 70
pixels wide by 94 in height.
The
WorldWide Telescope Data Files Reference document contains a full list in the Taxonomy appendix
for use with the Classification Taxonomy entry. Properly
classifying guided tours will help users locate the tour when searching.
(Note the search feature currently only applies to tours added to the
default collection).
|
Tour Editing Pane
Click OK to close the Tour Properties dialog and bring up the tour editing pane:
Adding slides to your tour could hardly be easier. Simply navigate to where you want to be and click Add a Slide.
Note that when you do this a thumbnail image of the current view is taken, and added to your tour.
You can change the view using the Look At and Imagery
lists between slides though if you do the tour will jump sharply from one image
to the next and not scroll smoothly.
The key editing elements are to the right of the image above. Tour
Properties will bring up the original properties dialog, for editing.
Music, Voiceover, Text,
Shapes and Picture items can be added to the slide. The
Show Safe Area checkbox can be used if you are using a wide
screen, but plan on the tour being fully visible to users of narrower screens -
checking it simply shades out the wider area.
- Music: MP3 and WMA files are the supported formats for both music and
voice. Browse for a suitable piece. Note that there are not fade-in, fade-out or
other sound effects available in WorldWide Telescope, so applying effects must be
done independently in audio editing software. Only volume can be adjusted while
editing a tour. If a piece of music is attached to
an individual slide, and the piece
is longer than the slide display time, the music will cut off suddenly at the
end of the
slide. The recommended approach is to attach music to the starting Master Slide,
so that the music
runs without glitches throughout the tour. Start by completing a silent
version of the tour, so you know exactly how long the tour is, then
locate suitable music and apply fading and perhaps other effects (using
quality music editing software) and finally apply it to the tour when
the music and tour are in a completed state. Note that the entire
music file is embedded in the tour binary, so it is a good idea to fade
out and
truncate the music at exactly the right time, so as not to store
unnecessary data.
- Voiceover: Use a similar procedure as for music, recording
and editing the audio using quality software. The Sound Recorder
accessory provided with Windows can be used to create voiceovers if you
have a microphone attached to your computer, but without any editing
features it is of limited utility. The difference between voiceovers
and music is that voiceovers should be applied to each individual slide, to get the
timing right. Both music and voice can be rendered simultaneously,
though adjust the volumes appropriately.
- Text:
Enter the text into the dialog, along with font and color information. Note that
the text can be resized on the slide, so there is no need to get the point size
perfect within this dialog.
If a background color is required for the text, select one after clicking on the
palette icon in the text dialog. Add line breaks by pressing ENTER where
required.
Click Save to add the
text to the slide. Then use the resize and rotate handles as necessary.
 | To select white as a color, click
on any of the white space around the color picker. The two colored boxes at the
bottom of the color picker show the old and new colors respectively. |
- Shapes:
Circles, rectangles, open rectangles, rings, lines, arrows and stars are
supported shapes. Once added to the screen, edit some of their properties using
the right click menu shown below.
 |
Use the Bring to... and Send...
options to layer multiple images appropriately.
Selecting the Color/Opacity entry will bring up the color
picker dialog
shown above.
Selecting Hyperlink will add a URL to
the tour. If the user clicks on the shape, the URL will be opened in the
default browser in a separate window. Note that no indication that this is a
link is provided automatically -- this indication should be provided by the
tour author.
Animate enables the movement, recoloring and resizing of text, shapes or pictures. To animate an
object, first move it, size it and color it at the location in the view you wish it to start. Then click
Animate. Then drag the object to the location you wish the animation to end, and
recolor and resize the object if
required. Then deselect the object. Animations are only enabled between a starting point and an ending point.
Right-click the slide you are working on, select Preview Tour From Here... and test the animations. Each
animated object should smoothly move, recolor and resize over the time period assigned to the slide. |
- Picture: Jpeg, Tiff, Png and FITS still images can be added to the
slide. Similar to text and shape entries, picture entries can be resized and
rotated on the slide. The same right click menu available for Shapes
can be used with pictures.
Slide Editing Menu
Some editing options are not quite so visible. Right click on a slide to
bring up a menu with a range of detailed options:
 |
Merge Tour after slide... will insert another tour to
become part of the tour being edited.
To set the start and end camera
position for a slide, simply navigate to the required angle, then click Set Start Camera Position. Then
navigate to the required ending angle, and click Set End Camera
Position. When the slide is shown in the tour, the view will
smoothly animate from the starting to ending positions.
Use
Capture New Thumbnail to replace the thumbnail image of a selected
slide.
To add a slide for a particular time -- say to capture an
eclipse or a crescent moon or a certain alignment of a star or planet, for example -- go through the following
procedure:
- Click View then open the Date Time Selection pane from the
Observing Time pane.
- Click the push-pin icon in the Date Time Selection pane
to undock it.
- Use the arrows to select the required time. Click Apply
as many times as necessary to locate the exact time you want. Do not click
OK so the Date Time Selection pane remains open.
So far you have not edited the tour, but just selected the right data and
time.
- Click the tour title bar to return to editing the tour. Create the new
slide if it does not already exist and ensure the slide that the date
and time applies to
is highlighted with a yellow outline. Right-click to bring up the editing
context menu, and ensure
Track Date/Time/Location is selected.
- Right-click the slide again to bring up the menu again, and this time select Set Camera Start Position.
- In the Date Time Selection pane (that should still be
storing the required date and time for the camera), click
OK. This edits the tour and applies the date and time to
the slide.
- Preview your tour to ensure you have done this procedure
correctly.
|
By default each slide will appear for 10.0 seconds. To change this click on the
pane just below each slide, and use the up and down arrows to change the number
of seconds.
 |
As an alternative to using the up and down arrows, mouse over the time
itself, and edit the numbers by hand.
Note that the time taken for a
tour is greater than the sum total of times for each slide, as the
transition times from one slide to another are included in the total run
time. |
Before progressing to add more and more slides, first consider creating a master slide. Master
slides are templates that are applied to all subsequent slides, containing
watermarks, logos, copyright messages, and so on. One tour can
have one or more master slides -- so the master slide can change as the tour
progresses, though only the most recent master slide applies to any one slide in a
tour. All music, voiceovers, text, shapes and pictures on a master slide will be applied to all
subsequent slides.
If background music is to be applied to your tour, consider starting the tour
with a master slide with a display time of only a second or two, and attaching
the music file to this one slide.
To make a slide a master slide, right click to bring up the context menu,
then select Master Slide. A bold M will appear
on the thumbnail. To revert a slide to normal status, bring up the menu and
click Master Slide again.
Slide Title
To add a title to a slide, click on the area below the thumbnail but inside the yellow bounding rectangle, and type up
to 15 characters as a title, for example:
 |
Note that a selected slide can be dragged and dropped to a new location in
the displayed list of slides. |
Control Views and Settings
To change current view settings for your slides, go into the View
or Settings menus and make the appropriate changes for the
selected slide (for example, to turn Constellation Figures or Boundary lines on
or off). To go back to editing the tour, click on the name of the tour in the
menu bar.
View and Settings entries can be changed
for each slide.
Completing the Tour
Click Save in the tour editing pane to save off the tour at any stage. Close the tour when it is completed by
clicking the X by the name in the menu bar:
Tours can be sent by email to friends and colleagues. A tour is stored in a .wtt
file, and can be sent as an attachment to a normal email. The file size of the
tour should obviously be below the limit applied by your ISP.
Well produced and interesting tours could also be submitted to a community
you are a member of, or for consideration by Microsoft Research for inclusion in WorldWide Telescope
itself.
See Also
An interactive tour is a tour where the user is required to give feedback.
This feedback could be in response to a menu of possible selections, such as in
a quiz with multiple choice answers, or even as simple as "where do you want to
go from here?". The main difference between an interactive tour and a normal
tour is that an interactive tour will not follow a set sequence of events, but
will instead jump from one stop on the tour to another that has been selected by
the user, or is in response to input from the user.
The basic process for creating an interactive tour is very similar to that of
creating any other tour, this section just covers the differences. So if you are
not familiar with the process of creating a tour, start with the Creating a Tour section.
Scenarios for interactive tours include providing "Back" buttons in normal
tours, creating coursework quizzes - perhaps at the end of a normal tour, the
students can be quizzed on its contents, and in providing some control over the
flow of a complex or long tour.
Tour Menu Selection
The following images shows a typical menu system that might appear in a quiz.
The blue text entries are all links to other slides. The white text entries are not
linked to other slides.
 |
The question (or menu) slide. |
 |
Three text entries in the question slide are linked to the "Wrong"
answer slide: Mars, Mercury and Pluto.
The "Try again" text will
return the user to the question slide. |
 |
Only the correct text entry on the question slide is linked to the
"Correct" answer slide: Venus.
The "This is Venus" text will more
the user onto the next question. |
In order to create the menu system shown above, first create all the
required slides with the appropriate text on them. Next right click on each text
entry in turn, and click on Link to Slide, this will bring up the
following dialog:
 |
Slides can be linked to another specific slide with the Link to Slide (Select below)
option. This is the appropriate selection for all the menu entries - linking
"Venus" to the correct slide, and the rest to the "Wrong" slide.
The
"Wrong" slide may be used many times, so its "Try again" text should be
linked to Return to Caller - so the user will be returned to the
question they got wrong.
The correct answer slide will probably be
linked to the next question with the normal Link to Next Slide option. |
Any of the overlays - text, shapes or pictures - can be turned into
active links. There are a few things to consider when creating an
interactive rather than normal tour:
- Master slides apply to the slides that follow it in linear order,
not necessarily the order that the slides will be displayed. Consider
making
every slide that links to, or from, a slide out of normal sequence a
master slide.
- In order to prevent the timeout of a menu slide (or any slide with
links on it that a user should select one of) from simply moving on to
the next slide, link that slide to itself. For example, the menu and
"Wrong" slides should link back to themselves, however the "Correct"
slide can simply timeout and move on to the next question slide.
- Music will not necessarily be rendered smoothly when the user jumps around the slides.
- Links can be applied to entire slides, rather than to overlay entries.
For example, instead of the "Wrong" slide having a "Try again" button the
slide could be linked with Return to Caller, in which case
it would simply timeout and then return the user to the question slide. Or
of course, both systems could be used.
See Also
Clicking on the down arrow below Guided Tours opens up the
menu entries.
|
Tour Home, Tour Search Web Page, and Music and
other Tour Resource link
to Microsoft Research WorldWide Telescope websites.
To play tours in demo mode (that is, in a continuous loop) select
Auto Repeat then one of:
One: play the selected tour
continuously
All: start with the selected tour, and cycle through the
other tours in the top pane continuously.
Undo and
Redo are enabled appropriately while editing a tour. |
See Also
Communities are public or private groups that can share data using WorldWide
Telescope.
Communities are great places to meet and share information with people who share your astronomy interests. Often
communities are associated with product manufacturers, telescope manufacturers
for example, or scientific communities, such as Harvard/Smithsonian or NASA.
Many communities let you join even if you do not purchase their products or belong to their institution, but joining
requirements will vary depending on the community.
You can also create your own community, populate it with items that are of specific interest (tours, images, links to
blogs, and so on), and email a community link to your colleagues so they can join in.
Joining a public community can be done both from the community menu, and from the community collection, by selecting Join
a Community. This will link you to the WorldWide Telescope website:
Click the links on this website to join one or more communities. After you join a community, its logo displays in the top
panel when you select Communities and when you want to connect to it, just click the thumbnail logo, and enter any
log in information, if necessary.
To join a private community, click on the .wtml file that you should have
received by email. If the community has been set up correctly, this will open
WorldWide Telescope with the associated community collection data
visible.
See Also
Creating a community involves writing .wtml data files, so this is covered in the Communities section of the
WorldWide Telescope Data Files Reference document.
This document also covers the creation of a community payload file -
which contains all the data (tours, images, and so on) that are particular to
the community. To add items to a community, an appropriate process (hand editing
or automatic) has to be agreed on and created to update the payload file.
Administering a community takes some computing and network expertise.
See Also
There are several methods of searching WorldWide Telescope data. Currently
only default data is searched, not data that may have been added to your own
collections, community data, and so on.
WorldWide Telescope includes the following catalogs in its internal index:
- NGC: New General Catalog
- IC: Index Catalog
- M: Messier Catalog
- BSC: Bright Star Catalog
- PGC: Principal Galaxy Catalog
As search options are scanning the data on the WorldWide Telescope server, you must be connected to the internet for
this feature to work.
See Also
The Search panel is exposed by clicking on Search.
To search on a name, such as Polaris or M51, enter it
in the text box top left. As you type the characters the search will be
automatic and fill out thumbnails as image data is found.
Alternatively, enter an RA and Dec if you
know the approximate location of the object you are searching for. The
default units are hours. In fact you can enter 23148, 2h31m48s, 2,31,48 or
02 31 48 -- any one of these means 2 hours 31 minutes 48 seconds. To enter
degrees, enter a "d", for example 89d 15m 51s. These particular
co-ordinates, if used for RA and Dec
respectively, are the location of the star Polaris.
Click Go to change the view to that location, then click
Search View for a search of the current view to be
carried out, with the results again displayed in thumbnail images. In addition to
this, if you check Plot Results, then the search results
will appear both as thumbnails and circle annotations in the view. For
example, entering 20 for RA, 18 for Dec,
clicking Go, Search View and Plot
Results, will reveal a constellation full of objects, as shown
below. Use the Finder Scope to further identify the objects.
|
See Also
Clicking on the down arrow below Search opens up the menu
entries. Not all are currently enabled.
 |
Selecting SIMBAD Search... will open up a small dialog
enabling you to search the SIMBAD database with a name. If the name is
located the view will change to the location provided in the database.
Selecting VO Cone Search will open up a more complex
dialog that will search Virtual Observatory databases based on RA, Dec or
registry titles. |
See Also
The View pane and menu entries contain a range of settings
that affect the current view.
See Also
The entries in the Constellation Lines and Overlays box apply when
exploring the Sky.
 |
Checking Figures indicates that constellation figures
should be rendered. Click on the colored line (red by default in this case)
to change the color or opacity of the lines.
Checking
Boundaries, Focused Only (the
constellation in focus), Equatorial Grid,
Ecliptic Orbits similarly determines whether to render
these lines and in what color.
Astronomers refer to crosshairs as a
reticle, checking the Reticle/Crosshairs option will turn it on or off.
The Field of View Setup matches a range of telescopes and cameras to the
rectangle size that indicates the field of view. The checkbox will turn this
on or off. |
See Also
The entries in the 3d Solar System box apply when exploring
the Solar System.
 |
Selecting Show Stars will display a large number of the
nearby visible stars, as light sources in 3D. Zoom rapidly out from the
Solar System to navigate the star formations.
Selecting Milky Way
will display the brightest stars of the Milky Way galaxy as a light sources in 3D.
Selecting Cosmos will display
much of the Universe as 3D light sources, though there can be performance implications with this
option, because of the huge quantity of data.
Selecting Orbits will
render a line showing the orbits of the planets (not the moons). The
color and opacity of the lines can be changed.
Sky Overlays
is not currently implemented.
Selecting Lighting will render the lighting effects of the
Sun. |
Neptune - without the Milky Way but with nearby stars:
|
Neptune - with the Milky Way (just visible as a blur) and nearby stars:
 |
To view the Milky Way and the Cosmos, use the mouse wheel to zoom way
out from the Solar System. To help identify stars and galaxies right click
on the objects to bring up the Finder Scope:
 |
Pluto - no lighting effects:
|
Pluto - with Sun lighting:
 |
See Also
The entries in the Observing Location box apply when
exploring the Sky.
 |
The Observing Location pane is used to set the viewpoint on
Earth. You can either select a Data Set and Region,
say to obtain the viewpoint from a city (such as Edinburgh, UK in the example
shown), or you can simply enter a longitude, latitude and elevation.
Check the View from this location box to obtain the new
view. If the Edinburgh location is selected, the new view is shown in the image
below. Note the horizon line. To show the full sky without the horizon, uncheck
the View from this location box.
|
View from Edinburgh UK:
 |
Viewing from a new location
Note that changing location does not change the observing time to
local time from that location. To view the sky from a new location in local time
first close WorldWide Telescope, then set your computer clock time zone to that
of the new location. Then restart WorldWide Telescope and then set the observing
location. This will ensure, for example, the correct rise, transit and set times
for the planets, moon and stars - from that particular location.
See Also
The entries in the Observing Time box apply when exploring
the Sky or the Solar System.
|
Use the Observing Time pane to change the time of the current view, or to greatly accelerate or decelerate the simulated time.
The movement applies to the Sun, and the planets and moons of the Solar System.
One specific use of this feature, is in viewing the shadows from past or future
solar eclipses on the Earth (see the Tutorial: Tracking a Solar Eclipse).
The date set must be between the limits of 0001/12/25 and 4000/12/31.
Simulated time will freeze if it reaches one of these limits.
|
See Also
Clicking on the down arrow below View opens up the view menu
entries.
|
Use Reset Camera in any view to recover the default view.
The
Startup Look At sub-menu enables the selection of which
mode to start up in. Sky is the default.
Copy Current View Image takes a snapshot of the current view, without
any UI elements. and copies it to the clipboard, Use it to paste into image
editing software such as
Microsoft Paint, or into an email, for example.
Copy Shortcut to this
View copies a URL to the clipboard, that can be emailed to another user of WorldWide Telescope.
Refer to the Sharing Views
section of the WorldWide Telescope Data Files Reference for
specific details of the format of the URL.
The Image Stack is currently an incomplete feature.
The Stereo sub-menu gives a range of options for 3D
viewing. Anaglyph requires the use of red and cyan, or blue
and yellow, 3D glasses. The
Side by Side options are used with twin projectors.
 |
See Also
The Settings pane and menu entries contain a number of
entries that affect the current view, and there are a few performance and
operation settings.
See Also
The Constellation Lines settings apply only to the Sky view.
 |
Use the Constellation Lines pane to create your own library of constellation
figures. These are the lines that by default are shown in red, and map out the
figures that the constellations are most famous for (the W of Cassiopeia, for
example). To create your
own library (which does not delete or replace the default library) go through
the following steps:
- Click Settings. Then click New in the
Constellation Lines pane.
- A small Figure Library Name pane will appear, so enter an appropriate
name. Click OK.
- The Constellation Figure Editor pane will open. Click on the name of the
first constellation that you want to create a new figure for.
- In the main view right click where you want to add a point, and draw the
new figure.
- Select the next constellation in the Constellation Figure Editor, and
repeat step 4, until you have added all the new figures.
- Click Save at the lower left of the Constellation Figure Editor to save
off the new figures.
When you next run WorldWide Telescope, the new figure set will be available in this pane. Notice that the default set
is available too, and remains unchanged. The Edit button can be used to add points for any selected constellation, and the
Delete button can be used to delete the entire library. The
Delete button in the Constellation Figure Editor
will delete the figure for the selected constellation.
|
See Also
The Earth and Planets settings apply to the Earth, Planet, and
Solar System views.
 |
The Show Earth Cloud Layer option obviously only applies when
viewing Earth, and then only in the Earth view (not in the 3D Solar System
view). Note that removing the cloud layer will not remove any clouds
that were present when the satellite images of the Earth were taken.
The Show Elevation Model option can be used
to apply elevation detail, if such detail data exists for the planet or
moon.
The Multi-Res Solar System Bodies option applies higher resolution textures
to the planets, if these textures are available. |
Earth without a cloud layer:
 |
Earth with a cloud layer:
 |
Mars without elevation detail:
 |
Mars with elevation detail:
 |
Venus without high resolution textures:
 |
Venus with high resolution textures:
 |
See Also
The Experience settings apply to all of the views,
containing settings that affect mouse operation, panning and zooming, and the
appearance of the UI.
 |
Zoom Speed obviously changes the rate at which the view is zoomed when using
the mouse wheel.
Changing Image Quality is not often apparent,
except when viewing the Earth close up.
Setting Smooth Panning avoids
sharp stops when releasing the mouse during panning.
Normally zooming
is focused on the center of the view. Checking Zoom on Mouse will zoom
centered on the mouse position.
Checking Auto Hide Tabs or Auto Hide
Context will remove the upper and lower panels respectively when the mouse
is not over them. To return them to view simply move the mouse over where
they normally are.
Un-checking Transparent Tabs will change the glass
panels to opaque.
Antialiased Lines applies to the colored
constellation lines that appear when viewing the sky at a distance. Checking
this might help give less jagged lines on a small resolution screen.
|
See Also
The Network and Cache settings do not apply to any specific
view, but apply to the connection with the Internet.
 |
A proxy server is not used by default, and the default port used to connect
to the internet is port 80. Change these only if necessary.
Use Manage Data Cache to clear local copies of images,
tours or catalogs. Most of this data is not stored locally by WorldWide
Telescope, but downloaded when requested or needed. However, after
downloading this data once, a local copy is kept in what is called a
Cache. The second time this data is requested, the cached copy is used
rather than a new copy downloaded. This system of caching data is frequently
used by web based programs. If you want to free up disk space, or perhaps
you know that data has been updated and you wish to ensure that the latest copy
is downloaded, then purge the data in the cache.
|
See Also
Clicking on the down arrow below Settings opens up the menu
entries.
 |
Check for Updates... will compare the version number of the program running
with the latest available.
Product Support... links to the WorldWide
Telescope website Support page.
Restore Defaults restores the default
settings in the View and Settings menu, but does not adjust the current
Observing Time.
Select Your Language... changes the language of the
UI.
Advanced brings up a sub-menu, that might be
helpful when troubleshooting your installation of WorldWide Telescope. Most
images are not stored locally in WorldWide Telescope, but are downloaded
from the Internet as you navigate through the sky. Show Download
Queue shows the current image tiles being downloaded. The queue can
be stopped, started again, flushed (all items are removed from the queue) and cleared
(all items are removed from memory). Refer also to the section on
the Network and Cache.
Show Performance Data
adds a small number of performance metrics to the title bar (such as frame
rate).
Master Controller: refer to the Multi-Monitor Cluster section.
|
See Also
It is possible to control and track a physical telescope connected directly
to your computer with a USB cable. With everything working correctly it is
possible to both move the view of the physical telescope and have WorldWide
Telescope mimic the movements and display the virtual view, or to change the
view within WorldWide Telescope and have the physical telescope's motor drive
change its position and display the actual view. In order to do this the
physical telescope must work with the ASCOM Platform software.
Note that there are some practical considerations to setting up this system.
The physical telescope obviously needs to have a good view of the sky, which for
most users means an outside location, and at the same time the computer needs
internet access for WorldWide Telescope to function, and both systems need
electrical power. Also note that most telescopes are not digital, the electric
power is only controlling the movement of the hub, the actual view from the
physical telescope is not stored digitally and cannot be transferred to the
computer.
See Also
The first step in controlling a physical telescope is to install the ASCOM software:
- Click on Telescope to open up the telescope panel. Note the ASCOM logo to the far right of the panel, with the
words Not Installed underneath it.
- Click on the ASCOM logo to follow a link to the ASCOM Standards for Astronomy page, and download the ASCOM Platform:
- Go through the download and installation procedures. This may take a few minutes.
- Confirm that the software has been installed by ensuring the word Installed now appears below the ASCOM logo in
WorldWide Telescope. Close and restart WorldWide Telescope if necessary:
To ensure that the ASCOM software is working correctly with WorldWide Telescope, test it in simulation mode:
- Click the Choose button on the telescope panel, then scroll down the list and select
Simulator:
- Click OK.
- Now click Connect on the telescope panel. You should
notice that many of the Telescope Control entries are now
enabled. The actual buttons that are enabled depends on the setup of the
simulator. Click Setup on the telescope panel. Change the Equatorial System entry in the Advanced
section to J2000:
- Click OK in the Setup dialog and you should notice that a new window has been opened, the Scope Simulator.
This window mimics the remote control of a physical telescope:
 |
 |
Open up the Scope Simulator and ensure that there are red
numerical position values. If there are not, as seen in the image to the
right, then the simulator did not start correctly. Workaround seems to be to
close WorldWide Telescope and try again. |
- Next click on Search to open up the search panel, then enter Polaris into the search text box. When the
thumbnails appear, double click on Polaris (not Polaris Australis). This will instantly change the WorldWide
Telescope view to the star.
- Click on Slew in the telescope panel. You should see the settings on the Scope Simulator change to the
RA and Dec of Polaris:
- Next select the controls of the Scope Simulator -- one or more of N, S, E or W. Note
that holding down Shift will move the virtual scope slower, and Ctrl even slower. So make some key presses to move the
simulated view. Note the change in RA and Dec.
- Click Center in the telescope panel to center the WorldWide Telescope view on whatever the simulated telescope is
viewing. You should see the view smoothly animate to the simulator's settings.
- Pressing Traffic on the Scope Simulator will display a window giving a log of the telescope movements:
- This completes the simulation test.
The next step is to set up the physical telescope and your computer in a location that will enable you to align the telescope
correctly. Align the telescope before attaching it to the computer with the USB cable. Telescope alignment can be involved
depending on the technology used by the telescope software. When it is correctly aligned:
- Ensure the computer and telescope have an adequate power supply.
- Point the telescope at a well known star, Polaris for example.
- Attach the telescope to the computer with the USB cable.
- Select Choose in the telescope panel, and select the type that best matches your telescope:
ASCOM Dome Control, Generic Hub and so on.
- In Setup check off the items that best match the features of the telescope.
- Select Connect, and this should enable the Telescope Control pane of the telescope panel.
- Click Slew to change the WorldWide Telescope view to match that of the telescope. Use the Finder Scope
to verify that the WorldWide Telescope view is the same as the physical telescope, Polaris for example.
- If the telescope alignment is at any point uncertain, use the Sync option. This transmits the RA and Dec of WorldWide
Telescope to the physical telescope.
- Use WorldWide Telescope to locate objects close to the original alignment, then Slew the physical telescope to
the new location to try to view it for real! Alternatively control the physical telescope and use WorldWide telescope to
identify the objects you locate.
See Also
See Also
Clicking on the down arrow below Telescope opens up the menu
entries
See Also
There is more information available within WorldWide Telescope that a
newcomer can easily grasp, and there are terabytes of astronomical information
available on the Internet. This section describes the features and data within WorldWide
Telescope that experienced astronomers should find helpful in their studies.
See Also
A Collection is the term used to describe a WorldWide Telescope data file. You can create your own collections,
either from existing images or perhaps from your own data. As long as the data that the new collection references is available
on the internet, your new collections can be shared.
To create a new collection, either select Explore > New > Collection..., or select
Collections > My Collections > Add New Item, which has the same
effect. Enter an appropriate name in the
Create New Collection dialog box. Your new collection will be added under My Collections and the data will be saved off automatically when you add
new images to it.
To add images to this new collection use the Research option of the Finder Scope,
which has an Add to Collection menu entry. If you select the Add New Item
thumbnail when the new collection is displayed in the
top panel this will add a new folder to your collection, enabling a
folder and image structure which might be helpful for a large or complex
collection. Add as many folders and images as you like to the collection.
To edit the metadata for any one of the images, right click the thumbnail
for the image, and select Edit. This will bring up the Edit Object Information dialog:
 |
Some of the metadata information is populated, including the
Constellation and RA and Dec
co-ordinates, when the image is added to the collection. Clicking
FromView will overwrite this with the co-ordinates of the
current view, so be careful of clicking this inadvertently.
Add
appropriate Names and Classification. |
Your own collections are saved to the My Documents/WWT Collections folder. Each time you add an image to a collection
the file is updated. If a collection is moved to another location, you can open if by browsing to it
using the Explore > Open menu option.
Note that by right-clicking on an image in one of your collections, the Remove from Collection menu option is available
for you to delete images. To delete or rename a collection, right-click the collection thumbnail.
To move images around within a collection that contains folders, use the
Add to Collection option to add the image to the right folder, then
Remove from Collection to delete the image in the wrong folder.
To share your collection with other users, email the .wtml file in the My Documents/WWT Collections
folder. The users that receive this email can either double click on the wtml
file (if the file mime types have been set up appropriately) to open up
WorldWide Telescope with this collection, or simply use Explore > Open
to navigate to and open the collection.
See Also
Astronomers often use comparisons of images of different wavelengths of an object to help expose information about that
object, such as the type of gasses being emitted, the blue or red-shift, the intensity of x-rays or gamma rays, and so on.
WorldWide Telescope has the concept of a study - usually a single or composite image of one object in space, and a
survey - usually a comprehensive collection of data from a large area of the sky. Typically a study is loaded
from a Collection by clicking
a thumbnail in the top panel, and a survey is selected from the Imagery list. In this context the study is the
foreground image and the survey the background image. There are options to reverse this, or to compare two
studies or two surveys, but the study on top of the survey is the default operation.
When both a foreground and background image are in view, the Image Crossfade slider appears, enabling you to visually compare
the two images:
Another method of comparing images is available if there are several thumbnails (studies) of the same object. For example,
select Explore > Collections > Chandra Studies and then scroll to Kepler's Supernova. There are a number
of thumbnails representing different studies of this feature, including the
visible wavelength and high energy x-rays. To compare the studies without any change in camera position,
click on the picture icons in the top right hand corner of the thumbnails:
 |
The
picture icon. |
To change the default operation of a study as foreground and survey as background there are a number of options.
All default
surveys appear as thumbnails in the Collections > All-Sky
Surveys folder. Simply clicking on the thumbnail will load the survey as
background. However if you right-click on the picture icon, there is the option
to load the survey as foreground or background. Load one as foreground and one
as background and the Image Crossfade slider will be enabled to compare the two.
Similarly two studies can be compared this way.
There are options in the
Finder Scope to set images as foreground or background, and then there is the
greater flexibility (and complexity) provided by the SDK (refer to the
WorldWide Telescope Data Files Reference document).
Note that not all images of an object are taken from exactly the same camera
position. Also sky survey images are composite images -- perhaps with
images taken at different times or even by different telescopes -- so the exact
location of an object may appear to vary.
See Also
The Finder Scope is a pane designed to help you fix on and
research a particular object. It can be opened by right-clicking on the view, or
from the Explore menu.
Certain celestial objects, when pointed to, display a circle and a name. This
indicates that the object is in one of the databases that WorldWide Telescope
links to. Right-click the object to display the Finder Scope. With the Finder
Scope, you can refine your search in the field of view, or research
your selected object from online references.
You can also view the object's image from the DSS or SDSS archive, download
its DSS FITS file, or run a USNO NVO cone search for objects near the selected
object.
If you find an object you wish to research further, try not to move the
Finder Scope as the RA and Dec will change, so if you then click
Research for example, this will use the new values and not those of the
object.
Note also that you can pan by dragging
the Finder Scope to the edges of the field of view.
 |
An object in space may have multiple names: Ksora and
HIP6686 in the example shown.
Click Show object to return to the view of the object if
for any reason the view no longer shows it.
The properties of the
object (RA, Dec, Alt and so on), are explained in the Astronomy Terminology tutorial.
Refer also to the note: Viewing from a new location.
Both the X
in the top right corner, and the Close button,
close the Finder Scope. |
 |
Click Research to bring up a menu of options to research
websites for data or more images of the object.
The Set as
Foreground Imagery, Set as Background Imagery, and
Remove from Image Cache will only appear in the menu if
these items are relevant to the selection.
Copy Shortcut can be
used to create and copy a URL locating the object that can be emailed to
friends or colleagues. Refer to the Sharing Views
section of the WorldWide Telescope Data Files Reference for
specific details of the format of the URL.
Add to Collection can be used to store the view in a data collection
file you are working on.
SAMP is an astronomy
protocol
for sharing data. |
Information
|
Note that informational websites are independent of Microsoft and may
require additional software, licenses or sign in procedures.
SIMBAD: the Set of Identifications, Measurements, and Bibliography
for Astronomical Data.
SEDS: the Students for the Exploration and Development of
Space.
Wikipedia: online encyclopedia.
ADS:
the Smithsonian/NASA Astrophysics Data System.
NED: the
NASA/IPAC Extragalactic Database. |
Imagery
 |
DSS: Digitized Sky Survey
SDSS:
Sloan Digitized Sky Survey
FITS: Flexible Image
Transport System image, commonly used in astronomy because of its
ability to store human-readable metadata.
|
Virtual Observatory Searches
 |
Refer to the Virtual Observatory Tables example below. |
SAMP options
 |
Send the image or
table data to Broadcast to be picked up by
all other SAMP compliant programs you are running. |
See Also
Virtual Observatory (VO) tables are spreadsheets of mainly numerical astronomical data,
layout to a standard set by the
National Virtual Observatory.
For example, use the Search Panel to navigate to the galaxy M51 -- much better known as the
Whirlpool Galaxy, and right click to bring up the Finder Scope, select Research > Virtual Observatory Searches
> NED. This will bring up the VO table shown below. Select Plot All in the VO Table Viewer to annotate
all the located objects in the view with the selected Plot Type
(white circles by default) -- a lot in the case of M51! Now use the
Finder Scope on the individual plots to investigate them further, many
will be unidentified electromagnetic wave sources.
VO Cone Search
A Virtual Observatory (VO) cone search is a search for data on objects in
space within a cone - specified by a direction into space and a radius. The diagram below shows a cone search with a
radius of approximately 8.5 degrees.
 | The cone search can be refined by specifying that only certain types of objects
("white dwarfs", "knots", "supernovae" etc.) should be located. |
 | First pan to
the area of space you wish to search, then zoom in to reduce the radius to
an appropriate amount.
Select VO Cone Search/Registry Look up
from the Search drop down menu.
Enter the search criteria (pulsar in the
example), and click NVO Registry Search to populate the table with data.
Further refine your search by selecting one of the rows in the table (to
locate the Base URL field), and click Search
to bring up a VO table.
|
Note the Web Client version has an additional option, to allow the
selection of either a catalog search, or a search for images using a
SAIP query.
See Also
The FITS (Flexible Image Transport System) was developed
particularly to hold the one, two and three dimensional data that is
particular to astronomy, with the requirement for a large amount of
metadata to be stored along with an image or table of data. For
specific details refer to FITS Data Format.
If a FITS image is loaded into WorldWide Telescope some additional analysis
options become available. To load a FITS image simply use the Explore >
Open > Image... option, and note that the Scale icon appears in the
lower panel alongside the Image Crossfade slider:
 | Click on the Scale icon to display a light intensity histogram. |
 | Slide the green and red bars to select the starting and ending
points for the display, then select from Linear,
Log, Power, Square Root to
determine how the data is to be displayed in the main view. Note that the
red bar can precede the green bar to invert the slope. The bars limit the
range of data that is to be displayed, and the slope determines the emphasis
given to the data.
The final option, Histogram Equalization, does not use
the bars, but instead gives equal emphasis to each intensity level of the
data.
Note that there are 256 intensity levels, from pure black on
the left margin of the histogram, to pure white on the right. The height of
any bar in the histogram indicates the number of pixels in the image at that
particular intensity level.
The
zoom in and zoom out options enable greater focus on a particular band of
data.
Using this tool particular light sources can be examined in
isolation. |
See Also
Comprehensive surveys of the sky have been carried out at different
wavelengths to help determine the composition of stars and galaxies. The digital images
generated by sky surveys are compiled into the data sets that are available in the Imagery
drop down list, and usually provide the background image to the view.
Each imagery set provides unique information about objects in the
sky because the images were taken at different wavelengths of the
electromagnetic spectrum, and at different times. Different wavelengths
expose different energy regimes, stellar processes, and effects. For
example, with observations made in the low-energy spectrum (radio and
microwave), cold processes are exposed: molecules forming or moving
about, or giant clouds of gas and dust. The optical band (between
infrared and ultra violet) exposes gas escaping from black holes,
volcanoes on the moons of Jupiter, or heat escaping from stellar dust.
With x-rays, hot processes become apparent such as explosions on stars,
neutron stars, comets, supernova remnants, or energy beams emanating
from matter falling into black holes. With gamma-rays, even more
violent events become apparent,
such as the destruction of atoms, stars spiraling into black holes,
supernovas, and pulsars.
Electromagnetic radiation is classified as follows:
Wavelength | Name |
| Greater than 10cm | Radio waves |
| Between 10cm and 1mm | Microwaves |
| Between 1mm and 700nm | Infrared radiation. |
| Between 700nm and 400nm | Visible light
 |
| Between 400nm and 10nm | Ultraviolet radiation |
| Between 10nm and 1/100nm | X-rays |
| Less than 1/100nm | Gamma rays |
Try selecting a specific object or an area of the sky and then changing
Imagery to compare
the object's properties. Astronomers have used the different wavelengths to
great effect, for example by using the hydrogen alpha wavelength to track stellar red-shift,
over 250 planets have been discovered.
Below is a description of the Imagery sets included
in WorldWide Telescope. Note that specific objects are not always
visible in every imagery set. For example, specific stars identifiable
in the Digital Sky Survey are not always visible to the unaided eye in
the Hydrogen Alpha imagery. Also, the different surveys have been
carried out at different resolutions. For comparison purposes, the
images below show the constellation Cygnus.
Imagery Data
See Also
A comprehensive sky survey in the visible wavelength, first published in
1994. This survey was created by the Space Telescope Science Institute's (STScI) Catalogs and Surveys Group from
images of the northern sky taken by the National Geographic Palomar
Observatory in California (from 1948 to 1958) and images of the southern sky
taken by the
UK Schmidt telescope in Australia (from 1973 to 1988). The original image data
was a large number of glass photographic plates, with each plate covering 6.5 x 6.5 degrees of the sky.
These plates have produced very large digital images (14000x14000 or 23040x
23040 pixels), and it is a compressed version of these images that WorldWide
Telescope accesses.
 |
See Also
Hipparcos is the name of a European
Space Agency Mission and Satellite that took images from 1989 to 1993 and
accurately catalogued 118,218 stars. Taken from space, the measurements
avoided the gravitational, atmospheric and thermal distortions that were
limiting ground based telescopes. The error in the positioning of stars in
this catalog is under 0.001 arc seconds. An auxiliary star mapper pinpointed
many more stars with lesser but still considerable accuracy at 0.03 arc
seconds. Known as the Tycho Catalog this identified 1,058,332 stars.
 |
See Also
The Very Large Array (VLA) Low-Frequency Sky Survey (VLSS) is an ongoing
survey of the sky for radio waves at 74 MHz (4-meter wavelength). The
radio survey consists of 358 overlapping images
covering the entire sky north of the -30° declination.
The survey has so far identified over 70,000 sources of radio waves.
From the survey, there are significant samples of objects including high
red-shift radio galaxies, galaxy clusters and supernova remnants. Very
distant radio galaxies may reveal information on the timeline of cosmic
events, such as how soon
black holes were formed in the history of the Universe.
 |
See Also
The Wilkinson Microwave Anisotropy Probe (WMAP) was a three-year, all-sky
survey that concluded in 2006. The survey was conducted at several microwave
bands (K, Ka, Q, V and W) to measure and map the cosmic microwave background
radiation, measuring both its intensity and by how much it fluctuates. Microwave radiation is the oldest light in
the Universe, and from this survey the Universe is estimated at 13.73
billion years old, to a 1% accuracy. Other results of the survey include
support for the theory that most of the Universe is made up of dark energy
(73%), with the rest mostly dark matter (22%) and only a small portion (5%)
as atomic.
 |
See Also
The Infrared Dust Map is an all-sky, 100 micron, far infrared (12, 20, 25, and 100 micron pass bands)
survey modulated by dust temperatures and then calibrated to be dust
reddening at various magnitudes. Dust affects optical light by effects known
as extinction and reddening. Extinction is the loss of
light due to scattering and absorption as it travels through clouds of dust.
Because the dust scatters blue light more than red, the color of the light
also changes - an effect known as reddening. When astronomers measure
distant stars, galaxies, supernovae, or any other light-emitting object,
they must correct the color and amount of light they measure for the amount
of dust the light has passed through.
 |
See Also
Starting in 1983 the Infrared Astronomical Satellite
(IRAS) - a joint project of the US, UK, and the Netherlands - performed
a survey of 98% of the sky at four wavelengths: 12, 25, 60, and 100 m.
IRAS led to numerous scientific discoveries spanning a broad range of
astrophysical subjects, from comets to circumstellar disks to
interacting galaxies. A new generation of IRAS images, called IRIS,
benefits from a better zodiacal light subtraction, an improved
calibration and zero level, and from a better de-striping. The data set
is used to study the variations of dust properties. Several studies of
dust emissions at high galactic latitudes show large variations of dust
properties depending on the grain sizes
of the dust. Large dust clouds are the birthplaces of stars and planets.
 |
See Also
The 470,992,970-source Two Micron All Sky Survey (2MASS) Point Source
Catalog was produced by a joint project of the University of
Massachusetts and the Infrared Processing and Analysis Center. The
entire sky was uniformly scanned in three near-infrared bands to detect
and characterize point sources brighter than about 1 mJy (1 milliJanksy) in each band.
2MASS used two highly-automated 1.3-m telescopes, one at Mt. Hopkins,
Arizona, and one at Cerro Tololo Inter-American Observatory, Chile. The
northern 2MASS facility began routine operations in 1997, and the
southern facility in 1998. The primary use of these maps is likely to be
as a new estimator of galactic extinction.
 |
See Also
A full sky map generated at Princeton University
compositing the Virginia Tech Spectral line Survey (VTSS) of the
northern skies and the Southern H-Alpha Sky Survey Atlas (SHASSA)
produced from images taken by the Cerro Tololo Inter-American
Observatory in Chile of the southern skies. The hydrogen-alpha filters
block out as much of the hydrogen emission spectrum leaving only a band
pass from 0.5 Angstrom to 1 Angstrom deep in the red end of the visible
light spectrum. The composite map can be used to provide limits on
thermal emissions from ionized gas known to contaminate
microwave-background data.
 |
See Also
The Sloan Digital Sky Survey (SDSS) was initiated in 2000 and is
ongoing. The survey uses a dedicated 2.5-meter telescope at Apache Point
Observatory, New Mexico, equipped with two powerful special-purpose
instruments: a 120-megapixel camera images 1.5 square degrees of the sky
at a time (about eight times the area of the full moon), and a pair of
spectrographs fed by optical fibers measure the spectra of (and hence
distance to) more than 600 galaxies and quasars in a single observation.
After eight years of operations this survey has obtained deep,
multi-color images covering more than a quarter of the sky. The result
has enabled the creation of 3-dimensional maps containing more than
930,000 galaxies and 120,000 quasars.
The survey has not yet covered
the constellation Cygnus, so the image shows the constellation Leo:
 |
See Also
The Tycho-2 catalog is based on a mix of 1991 space-based data from the European Space Agency's Hipparcos satellite, data from the Tycho 1 catalog,
and over 140 other astrometric catalogs. The catalog also included the re-analysis of positional data for the Tycho-1 stars.
The celestial co-ordinate data for all the earlier catalogs was corrected to
match the J2000 epoch of the Hipparcos catalog. The mix increased the number
of stars in the catalog to 2,539,913 of the brightest stars in the Milky Way, of
which about 5000 are visible to the naked eye. Components of
double stars with separations down to 0.8 arc seconds are
included.
 |
See Also
The US Naval Obersvatory-B1.0 is a catalog of 1,042,618,261 objects. The
data were obtained from scans of 7,435 Schmidt plates taken for the
various sky surveys during the last 50 years by the Precision Measuring
Machine (PMM) at the US Naval Observatory in Flagstaff, Arizona. The
originating plate material includes five complete coverages of the
northern sky and four of the southern sky To be included in the catalog,
an object must have been detected on two different surveys, to avoid the
unreliability of single detections. The Tycho-2 Catalog is the
astrometric reference. The USNO-B1.0 is believed to provide all-sky
coverage, completeness down to 0.2 arc second astrometric accuracy at
J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85%
accuracy for distinguishing stars from non-stellar objects.
 |
See Also
Since its launch in 2003, the Galaxy Evolution Explorer (Galex) telescope
has imaged more than a half-billion objects across two-thirds of the
sky. The telescope studies galaxies far beyond our Milky Way through its
sensitive ultraviolet telescope - the only such far-ultraviolet detector in space. The
Galaxy Evolution Explorer has two detectors: one in far-ultraviolet,
which reveals stars younger than about 10 million years old, and another
in near-ultraviolet, which detects stars younger than about 100 million
years old. Massive young stars burn their large supply
of hydrogen fuel quickly, burning hot and bright while emitting most of
their energy at ultraviolet wavelengths. Compared with low-mass stars
like our sun, which live for billions of years, these massive stars
never reach old age, having a lifespan as short as a few million years.
 |
See Also
The ROSAT All Sky Survey (RASS) was a survey of the sky
released in March 2000 by the Max-Planck-Institut für
extraterrestrische Physik. The survey was the first imaging X-ray
survey of the entire sky. Combining the RASS Bright and Faint Source
Catalogs yields an average of about three X-ray sources per square
degree. However, while X-ray sources are known to range from distant
quasars to nearby M dwarfs, the RASS data alone are often insufficient
to determine the nature of an X-ray source. The X-rays are mainly
emitted by some million-degree gases such as stellar coronae, supernova
remnants, superbubbles (a cavity hundreds of lights years across filled
with hot gas), and the hot plasma of the galactic nucleus. The faint
source catalog has 105,924 sources, and the bright source catalog has
18,811 - the distinction being that to qualify for a bright source
listing the source must emit 0.05 counts/sec or greater. Counts per
second (or CPS) is a measure of x-ray activity.
 |
See Also
Launched in 2008, NASA's Fermi Gamma-ray Space
Telescope is tasked with exploring extreme environments in the Universe. These
include the powerful explosions known as gamma-ray bursts (believed to
occur when massive stars run out of nuclear fuel), pulsars (neutron
stars emitting beams of radiation), solar flares, and the acceleration
of jets of material away from black holes. So far the Fermi
telescope has revealed a new class of pulsars, probed gamma-ray bursts
and watched flaring jets in galaxies billions of light-years away.
 |
See Also
Simply sets the entire background to black.
 |
Browse
You can also open equirectangular projected images as a background (refer to
WorldWide Telescope Projection Reference) by browsing to their location on your computer.
This option works in Planet, Sky and
Panorama modes.
Note that there are more surveys available in WorldWide Telescope than are included in the Imagery list. These
additional surveys are available in the Collections > All-Sky Surveys > More Surveys collection.
See Also
The Context Search automatically searches the
constellation that the reticle is currently on for deep sky objects that are
listed in a catalog, such as the Messier or New General catalogs. If it finds any objects, its
thumbnail image is added to the list in the lower panel. As you move the Field
of View (FOV) to a new constellation, the thumbnails for the deep sky objects
change automatically to reflect all the deep sky objects in the new
constellation.
To obtain some information on the items in the Context Search, right-click on
the thumbnails in the lower panel and select Properties from
the menu. This will display the same information that appears in the The Finder Scope,
for example:
 |
In this example M86 has appeared in the lower panel as a result of the
context search. Selecting Properties from the right-click
menu displays the property data without changing the view. |
Context Search Filter
You can restrict the list of deep sky objects displayed by the Context Search
to only those objects identified in the following table, by selecting items in
the Context Search Filter.
Click on the thumbnail images below to link to the example. And then click on
the thumbnails as they appear in the top panel to bring the objects into view.
Group | Title | Description | Example |
| | Solar System | The Sun, or any planet or moon of our own
Solar System. |
|
| Stellar | | | |
| | Star | A ball of gas held together by its own gravity
and emitting its own radiation. |
 |
| | Supernova | A star (at least 8
times more massive than the Sun) that does not have enough fuel for the
fusion process in its core will explode due to gravitational collapse.
The explosion is called a supernova. The remaining material is known as
a supernova remnant. |
Supernova Dust Factory in M74 |
| | Black Hole | A star (at least 10-15 times more massive than the Sun) that became a supernova and then further collapsed in on itself.
The infinite density of the supernova's remnants causes the path of light to wrap around it. |
Black Hole-Powered Jet of Electrons and Sub-Atomic Particles Streams
From Center of Galaxy M87
|
| | Neutron Star | The ultra-dense collapsed core of a star that has undergone a supernova. |
NASA Great Space Observatories Glimpse Faint Afterglow of Nearby Stellar
Explosion |
| | Double Star | Two stars that orbit around a common center of mass. |
 |
| | Multiple Stars | More than two stars that orbit around a common center of mass. |
 |
| Stellar Grouping | | | |
| | Constellation | A grouping of stars occupying one of the 88 areas in which the sky is divided.
Note that the search filter will locate only those items that have a
Constellation classification set on them, which does not include all
the constellations themselves, but studies relating to a constellation. |
Young and Old Stars Found in Andromeda's Halo |
| | Asterism | A group of stars that comprise a portion of a larger constellation whether physically related to it or not. For example,
the Big Dipper is part of the Great Bear constellation, and the Belt of Orion is part of the Orion constellation. |
 |
| | Open Cluster | A physically related
groups of stars formed from the same giant molecular cloud and held
together by mutual gravitational attraction. |
 |
| | Globular Cluster | A spherical collection of stars that share a common origin and orbit a galaxy as a satellite. Globular clusters are very
tightly gravitationally bound, which gives them their spherical shape. They are also extremely dense towards their core. |
 |
| | Nebulous Cluster | A diffuse mass of interstellar dust and gas that orbits a galaxy as a satellite. |
 |
| | Dark Nebula | An interstellar cloud of dust so dense that it obscures or absorbs light coming from stars or nebula behind it. |
No current examples |
| | Giant Molecular Cloud | A type of interstellar cloud whose density and size permits the formation of molecules, stars, and planets. |
 |
| | Interstellar Dust | Irregularly shaped, stellar material, just a fraction of a micron across, composed of silicates, carbon, ice, and/or iron
compounds. This material scatters light in our line of sight and obscures or obstructs our view of stellar objects. |
Nearby Dust Clouds in the Milky Way |
| Nebula | | | |
| | Nebula | A diffuse mass of interstellar dust
and gas. These areas result from supernova explosions and are the birthplaces of
new stars. |
 |
| | Planetary Nebula | A shell of gas ejected from stars, such as our Sun, at the end of their lifetimes. This gas continues to expand from the
remaining white dwarf. |
 |
| | Supernova Remnant | The remains of the explosion of a massive star such as a red supergiant. |
 |
| | Emission Nebula | A nebula that shines by emitting light on a hydrogen cloud. |
 |
| | Reflection Nebula | A nebula that shines by reflecting light from nearby stars. |
 |
| | Cluster of Galaxies | A group of galaxies that are gravitationally bound together. |
 |
| | Quasar | An extremely bright object
at the edge of our universe that emits massive amounts of radiation,
including radio waves and x-rays. |
No current examples |
| Galactic | | | |
| | Galaxy | A cluster of stars, dust, and gas held together by gravity. |
 |
| | Spiral Galaxy | A galaxy in which most of the stars are arranged in a disk and have spiral structures ("arms") that extend from the central
bulge of stars. |
 |
| | Irregular Galaxy | A galaxy that does not fall into one of the three main Hubble sequence galaxy classes. |
 |
| | Elliptical Galaxy | A galaxy that does not have a disk but rather a smooth, featureless profile. They range in shape from nearly spherical to
highly flattened. |
 |
| | Knot | An area within a galaxy containing a greater concentration of material (such as gas, dust, or stars) than adjacent areas. Knots
appear in images as bright areas within a galaxy. |
 |
| Other | | | |
| | Unidentified | Deep sky objects that have
not been identified or cataloged. |
 |
| | Plate Defect | Plate defects are
images containing photographic errors, such as the reflection of the
telescope, color aberrations, dust, and so on. The telescope is usually
reflected in an image when a single, very bright object is photographed. |
 |
| | Other NGC | The New General Catalogue is one of the most commonly-used catalogs in amateur astronomy and contains nearly 8,000 objects. |
 |
See Also
The value in comparing and cataloging the brightness of stars was
apparent to the ancient Greeks, who developed a system of six
magnitudes, the
brightest being level one, the dimmest level six. The difference
between each level was roughly twice-as-dim,
so a level six star would be 32 times as dim as a level one star. This
system was formalized much later so that a level six star was 100 times
as dim as a level one star, so the difference between each level became
2.512. As the Sun, Moon and Planets were not part of the system to
introduce them meant adding negative numbers, and to introduce stars
that are only visible through telescopes the scale was extended far
beyond six, and now goes from -26.73 for the Sun, to about 30 for the
dimmest stars visible using the Hubble Space Telescope. It is an odd
scale as it straddles zero, but the only important information in it is
the difference between
two numbers when calculating relative brightness - individual numbers
on their own have little meaning. The reference point (a magnitude of
zero) has
changed from the star Polaris, to Vega, to no star in particular as all
stars vary a little in brightness.
The value in this logarithmic scale is that it keeps the numbers in
a small range. If the brightness scale was linear and not logarithmic
it would have
to extend from zero to one trillion simply to include distant stars
(and ignoring the brightness of any object in the Solar System). The
following image shows the brightness of a number of stars around
Canopus (the second brightest distant star in our night sky):
 |
Tau Puppis
HR2400
HR2513
Canopus
HR2435
HR2554 |
2.93
5.6
6.57
-0.72
4.39
4.4 |
The brightness magnitude usually quoted for a star is the apparent magnitude, which is how bright it appears to us on Earth. The absolute
magnitude of an object is how bright it would appear at a standard distance away from the observer (a
distance which has been fixed at 10 parsecs or 32,616 light years). Both figures
are often quoted in catalogs of stars, the Finder Scope quotes only the apparent magnitude.
Apparent magnitude is often referenced as the letter V, absolute magnitude as
the letters MV.
To calculate the relative brightness of one object to another (either
apparent or absolute magnitude) use the following C# code:
private double calculateRelativeBrightness(double b1, double b2)
{
return (Math.Pow(2.512d, b2 - b1));
}
|
Using this program gives the following relative magnitudes of brightness:
First object | Second object | Relative Magnitude
(V scale) | Relative Magnitude
(linear) |
Sirius
(-1.46) | Canopus
(-0.72) | 0.77 | 1.977 |
Spica
(1.04) | HR5597
(6.37) | 5.29 | 135.552 |
Canopus
(-0.72) | HR2513
(6.57) |
7.29 | 1600.137 |
Alpha Centauri
(-0.01) | Proxima Centauri
(11.05) | 11.06 | 26559.333 |
Venus
(-4.7) | Neptune
(7.8) | 12.5 | 100056.530 |
Spica
(1.04) | IC3922
(14.8) | 13.76 | 319352.396 |
The Sun
(-26.73) | The full moon
(-12.6) | 14.13 | 449032.157 |
The Sun
(-26.73) | Proxima Centauri
(11.05) | 37.78 | 1,296,408,329,574,280.0 |
See Also
This section contains technical information on how to configure
WorldWide Telescope to run in environments other than on a single
desktop or laptop client computer.
See Also
A straightforward example of a multi-monitor cluster is to have a
single master computer, and a matrix of slave computers each rendering
a portion of the view.
 |
Hoag's Object - a rare ring galaxy - displayed on a 4 x 3 cluster. With a
resolution on each monitor of 1920 x 1200 the full image is 27 Megapixels.
The master computer is shown lower right.
|
To setup a multi-monitor cluster, go through the following procedure:
- Setup the hardware required, with each computer installed with
WorldWide Telescope. Each monitor is run by a single computer, so the
hardware setup may take some time, and require some additional
hardware, such as the support structure shown in the image above. The
computers must all be linked to the same local network. The
identification system
used for a matrix of computers and monitors is shown in the following
table (with the four by three matrix shown in the image above used as
an example):
| 0,0 | 1,0 | 2,0 |
3,0 |
| 0,1 | 1,1 | 2,1 |
3,1 |
| 0,2 | 1,2 | 2,2 |
3,2 |
- Some of the bios settings for each of the slave computer need to be changed.
This process is different for each make of computer - on some it involves pressing F2 during the startup process.
This will bring up a bios settings menu, and make the following changes:
- Ensure the Ethernet card is on. For example on a Dell computer, go to Power Management and set the Low Power Mode setting to Off.
- Enable a remote computer to start up this one. For example on a Dell
computer, also in Power Management set the Remote startup setting to On.
- Turn off any screen savers on the slave computers.
- If it is necessary to
remotely edit the config.xml files, then enable remote login. The following links may be
useful:
- For all the slave computers in the matrix create a configuration file
(called config.xml) in the root C: folder, with the following contents:
XML | Description |
| <?xml version="1.0" encoding="utf-8"?> | |
| <DeviceConfig> | |
| <Config> | |
| <Device | |
| MonitorCountX="4" |
The number of monitors in the X axis of the matrix. |
| MonitorCountY="3" |
The number of monitors in the Y axis of the matrix. |
| MonitorX="2" | The X
position of the computer in the matrix. The computer (shown
in bold in the table above) is shown as the example value. Note that
this index starts at zero. |
| MonitorY="1" | The Y
position of the computer in the matrix. Note that this index starts
from zero. |
| Master="False" | Set to
"False". |
| Width="1920" | The
desired screen resolution width for the slave. |
| Height="1200" | The
desired screen resolution height for the slave. |
| Bezel="1.07" | As the
physical edge of the monitors must be taken into account, certain
pixels will not be rendered (those that would theoretically appear
behind the
edges of the monitors). The Bezel factor is the ratio of the size of
the monitor to the size of the screen. An estimate of 107 percent is
used in this example.
The minimum Bezel value is 1.0.
 |
| ConfigFile="" | The
following three entries should be present, but with empty strings as
parameters. |
| BlendFile="" | |
| DistortionGrid=""> |
|
| </Device> | |
| </Config> | |
| </DeviceConfig> | |
- If the WWTRemoteControl utility is not being used, add WorldWide Telescope on the slave computers to
the start up list of programs for that computer (this is done through the
Control Panel).
- For large clusters consider adding a proxy server to the setup, such as an
ISA Proxy Server, to reduce the amount of traffic over the web.
- Finally, on the master computer, start WorldWide Telescope, and in the Settings > Advanced menu, select Master Controller.
From
now on the slave computers (when they are running WorldWide Telescope)
should display their section of the view on the master computer.
Restrictions
- Currently the slave computers will not show text or graphic overlays when playing a tour.
- The slave computers will not respond to changes in the View
or Settings menu - they will only run with the default
settings.
See Also
If remote control from a master computer of a single slave computer is
required, then create a confix.xml file on the slave computer such as:
<?xml version="1.0" encoding="utf-8" ?>
<DeviceConfig>
<Config>
<Device MonitorCountX="1" MonitorCountY="1"
MonitorX="0" MonitorY="0"
Master="False"
Width="1600" Height="1200"
Bezel="1.0"
ConfigFile="" BlendFile="" DistortionGrid="" />
</Config>
</DeviceConfig>
|
See Also
Remote Starting of the Multi-Monitor Cluster
With a large cluster such as the one shown in the image in the
previous section, it is helpful to automate the startup and shutdown of
all the slave computers from the master.
To do this use the WWTRemoteControl utility. For this to work though,
go through the following procedure:
- On the master computer run the WWTRemoteControl utility
program.
- Click the Node List button and add the MAC Address (physical address
component) of each slave computer to the list. To get the MAC Address of a computer, open up a command-prompt
window and type getmac. The address that is required is under the column Physical Address and should be six pairs of hexadecimal digits separated by hyphens.
- When the node list is complete, close that dialog and return to the main dialog.
- Click Wake All to turn on all of the slave computers.
- When all the slave computers have started, click Launch All to start WorldWide Telescope.
- When WorldWide Telescope is up and running on each slave, control the view from the master computer.
- Click Close All to finish the session and Shutdown
All to shutdown the slave computers.
- The node list is saved to the application properties for the utility, so
the next time it is run there is no need to re-enter the node list.
See Also
The following section applies to the use of WorldWide Telescope in
planetariums that use multiple projectors and a blended image. It does not apply
to a planetarium that uses a single fish-eye lens projection system - in which
case the program can be run without any changes to the configuration
settings. Also it does not apply to a planetarium using mirrors, such as the one
described in
WorldWide Telescope Planetarium.
Projection into a large planetarium is often done using six projectors, with each projector projecting onto an area of the dome
- with special blending done to mask the edges. The following diagram shows two
common six-projector projection layouts:
There are two methods of projection that can be configured in WorldWide
Telescope, the first using Projection Designer software, the second using an external blending
system such as Global Immersion®. One of the main
differences between the two is that blending is done by WorldWide Telescope
when using Projection Designer, but is usually done in dedicated hardware when
using external blending. The two methods
require different parameters in the config.xml file.
See Also
Follow this link for more detailed information on Projection Designer.
Use Projection Designer to calibrate and set blending parameters for the dome,
then define the configuration file as follows:
XML | Description |
| <?xml version="1.0" encoding="utf-8"?> | |
| <DeviceConfig> | |
| <Config> | |
| <Device | |
| MonitorCountX="1" |
Set to "1". |
| MonitorCountY="1" |
Set to "1". |
| MonitorX="1" | Set to "1". |
| MonitorY="1" | Set to "1". |
| Master="False" | Set to
"False". |
| Width="1" | Set to "1". |
| Height="1" | Set to "1". |
| Bezel="1.0" | Set to "1.0". |
| MultiChannelDome="True" | Set to "True". |
| DomeTilt="20" | Tilt of
the point of focus above the spring line of the dome, in degrees. |
| ConfigFile="path\configfile" | The
path to the Projection Designer configuration file. Refer to Projection
Designer documentation for the format and purpose of the files. |
| BlendFile="path\blendfile" | The path
to the Projection Designer blend file. |
| DistortionGrid="path\distortiongrid"> |
The path to the Projection Designer distortion grid. |
| </Device> | |
| </Config> | |
| </DeviceConfig> | |
See Also
Follow this link for more detailed information on Global Immersion.
Define the configuration file as follows:
XML | Description |
| <?xml version="1.0" encoding="utf-8"?> | |
| <DeviceConfig> | |
| <Config> | |
| <Device | |
| MonitorCountX="1" |
Set to "1". |
| MonitorCountY="1" |
Set to "1". |
| MonitorX="1" |
Set to "1". |
| MonitorY="1" | Set to "1". |
| Master="False" | Set to
"False" |
| Width="1" | Set to "1". |
| Height="1" | Set to "1". |
| Bezel="1.07" | Set to "1.0". |
| ConfigFile="" | The
following three entries should be present, but with empty strings as
parameters. |
| BlendFile="" | |
| DistortionGrid="" |
|
| MultiChannelDome="True" | Set to "True". |
| Heading="0" | The
left-right rotation of the projection, in degrees. |
| Pitch="0" | The up-down rotation of the
projection, in degrees. |
| Roll="0" | The rotate-left,
rotate-right rotation of the
projection, in degrees. |
| UpFov="0" | The field of view up
from the center point, in degrees. |
| DownFov="0" | The field of view
down from the center point, in degrees. |
| DomeTilt="20" | Tilt of the point
of focus above the spring line of the dome, in degrees. |
| Aspect="1.390531"> | Aspect
ratio of the projection, the ratio of width/height. |
| </Device> | |
| </Config> | |
| </DeviceConfig> | |
See Also
|