Go back! deutsch english español language

The Astra Satellites

blink with 2nd image

Date:16.10.1996 Time:18:05 & 18:19 UT Exposure:1s each
Field of View:4.6' x 4.0' Receiver:576 x 387 CCD Filter:Gunn R
Instrument: D=2m, f=5.6m Observatory: Pik Terskol, Caucasus Observer:N. Karpov, A. Sergeev, K. Jockers,
T. Credner, T. Bonev

© Copyright by the observers

The Astra satellites are a family of eight communication satellites in a geostationary earth orbit at an altitude of 36.000 km. Geostationary means that their orbit has a period of one sidereal day (about 23h 56min) and is in the equatorial plane, i.e. they do not move with respect to the earth.

The above image shows four of them as dots in the night sky (reflected sunlight). The telescope was not guided, so that background stars already appear as trails due to the earths rotation during the 1sec exposure. But the satellite orbits are not perfectly synchrone to the earths rotation, they are inclined and excentric. Seen from the earth they show a small elliptic movement during one day. Above you can blink two different exposures to show the satellites changing positions in 14 minutes.

  • The ASTRA Satellite System homepage