Geostationary satellites

Philip Chien (
Mon, 18 Mar 1996 04:15:45 -0400

Greg Roberts <> said:

>I find the mail referring to geostationary satellite visual observations
>of great interest. For the past 20 years I have been observing these
>satellites using either a 30 inch or 20 inch reflector at our Sutherland
>observing outstation of the South African Astronomical Observatory.


>Norad catalog numbers 19688,21139,22653,23331 and 23686 corresponding to
>ASTRA 1A,1B,1C,1D and 1E. Objects 19688 and 23331 appear to be the
>brightest and are suspected of being the two that merge every night.  I
>suspect the faintest satellite is #22653. However I would imagine these
>satellites are all of similar if not identical size so the variations in
>brightness amongst them are due to reasons other than physical size.

Actually they are different models and do vary greatly in size.

Astra 1A is a GE-4000 spacececraft bus
Astra 1B is a GE-5000

Astras 1C through 1F  (1F scheduled for launch in a couple of weeks on a
Proton) are based on the Hughes HS-601 bus.

There are different variations in the HS-601, and at least one Astra has
much larger solar panels than the others in the series.

The satellites are all basically box-shaped with fold-out solar wings in
the up/down direction, and two large circular antennas - one for
transmitting and one for receiving.

Philip Chien, Earth News - space writer and consultant  PCHIEN@IDS.NET
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