Geostationary satellites Astra and Hot Bird

12.3.2002, M. Rudolf

Sure you have already heard about the Astra telecommunication satellites; perhaps you even receive radio and TV programs from Astra with your satellite dish. Then you might be interested to see images of the geosynchronous Astra satellites which I shot on 12.3.2002:

The first image shows seven Astra satellites (as far as I know they are Astra 1B,1C,1E,1F,1G,1H,1K) as pointlike objects against the night sky. The streaks in the image are the trails of stars which have moved during this 15-second exposure.

The next image was shot with the camera following the movement of the stars, therefore the satellites appear as short trails whereas the stars remain pointlike.

If you receive your favorite TV/radio programs from Eutelsat - Hot Bird, have a look at the third image: it shows the Hotbird 1-5 satellites.

The Astras as well as the Hotbirds are in a geostationary orbit in a distance of ca. 36000 kms, straight above the terrestrial equator and at a longitude 19° east (Astra), or 13° east (Hotbird).

The above images have been obtained with a CCD camera and a lens with 900 mm focal length. Exposure time was 15 seconds, field of view is approximately 45x30 arcminutes.

As the geostationary satellites orbit around the Earth, they occasionally immerse into the Earth's shadow. The sequence below shows the Astra satellites disappear. The Earth's shadow approaches from the left (east) and gradually hides the satellites.

Note also that the positions of the Astra satellites relative to each other have changed, compared with the above pictures of the Astras which have been taken ca 2 hours earlier. The images were shot with 1 sec exposure time; some stars drift through the field of view from left to right during the exposures).

An animated GIF (230 kB) shows the immersion of the Astra satellites into the Earth's shadow from 22:17:35 to 22:20:43 UT. Images with 1 second exposure times were taken every 5 seconds for this animation.