This page shows a wide-field image of the night sky from Perth Observatory and is updated at an interval of about 10 minutes. An SBIG ST402 "All Sky Camera" is used to acquire the images. This instrument has a 90° by 140° field of view and provides a wide-field (fish-eye style) image of about 40% the night sky. The sky camera operates between approximately the evening and the following morning's nautical twilight time. This roughly corresponds to 7:00pm and 5:30am Western Australia Standard Time. That is, between 11:00 to 21:30 hours UTC (Co-ordinated Universal Time), and the last image will remain on this web site until the next evening's observing session.
Just an in real optical astronomy, clouds, light pollution, twilight, and moonlight will all effect the quality of the images. If the image quality is poor then return later or on another day. Beware, the Moon is so bright that it saturates the detector and distorts the images. However, it is possible to estimate the position of the Moon in the images and thus determine its motion with respect to the background stars. Clear images contain some useful information such as: constellations, star positions, meteors, comets, the orientation of the Milky Way, our galactic neighbours - the Magellanic Clouds or (sometimes) a new nova.
Additionally, a computer generated HA / declination chart of the sky imaged is provided. Hour angle (HA) is a co-ordinate that indicates the time interval until a celestial object is located at its highest in the sky. It is related to right ascension, the celestial co-ordinate equivalent to longitude on the Earth. Lines of constant HA have an approximately horizontal orientation and are separated by one hour in the chart.
Declination is the equivalent co-ordinate of latitude for celestial objects and lines of constant declination have an approximately vertical orientation in the chart. Northern objects are on the left hand side of the image. Also of note is the South Celestial Pole, the projection of Earth's rotation axis on the sky, at declination -90°. To the general public it is thought that stars rise in the east and set in the west. This is partly true - what is actually happening is that observers in the Southern Hemisphere will see the stars wheel around the South Celestial Pole during the course of the night. It is not the stars that are moving in this dramatic fashion - it is an effect produced by the Earth rotating about its axis.
This web page will be automatically refreshed about every 10 minutes. Hint: hold down the shift key while using the mouse on the browser's refresh (reload) button, if you wish to manually refresh this page.
This camera was purchased with funds from a SEED grant from the Astronomical Society of the Pacific.
Sky Camera Image
Star Chart Image
Other Useful Links
Time lapse movie of the night sky.
Current Perth Observatory weather data.
Current Perth Observatory weather data from the Bureau of Meteorology.
Current Perth region forecast from the Bureau of Meteorology.
Current Perth region weather data from the Bureau of Meteorology.
If you have any comments please them to Perth Observatory.
This page has been accessed times.
