These spacecraft are about the same length as a supermarket delivery truck..... 30-35 metres , and yet they can be seen using a modest telescope as the light from the sun plays on their solar panels.

There are now hundreds of communications satellites in geostationary orbit forming man made constellations in the night sky.

If a satellite is in geostationary orbit...does it move ?

Although satellites in geostationary orbit appear to stand still when viewed from earth , if we could travel out into space and get quite close to the spacecraft we would in fact see that they were continually drifting within an imaginary box about 100 km on each side.As the satellites get older , the rate of drift tends to increase as onboard fuel runs low.The position of each bird is closely monitored by ground stations , and when required , correcting burns are made to adjust the orbit.Eventually when the fuel state becomes critical a decision may be made to place the satellite into inclined orbit.Sometimes refered to as the "Comsat Manoeuvre" this series of commands places the spacecraft in an ever increasing figure of "8" orbit above and below the equatorial plane.

As the inclination increases over time , the satellite will become unusable for direct to home services , but can still be utilised by commercial ground stations to accommodate data , video and telephony communications.

In the following animation , which spans a period of about 40 minutes , the movement of two Eutelsat birds , thought to be Hotbird 1 and Hotbird 3 , are tracked.

This time lapse animation from October 24 2003 shows the movement of the five Hotbirds at 13 degs east over a period of about 80 minutes.

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Sun / Solar Transits

"Sun transit fades for geosynchronous satellites occur when the sun crosses the earth’s equatorial plane during the spring and fall equinoxes. At these times, the sun aligns directly behind the satellites for a few minutes each day....."

To learn more about Sun Transits , follow the link below to the website .....

When the sun tracks behind the geostationary arc ,satellite signals can be disrupted for some minutes .It would be great to image a group of satellites sihouetted against the solar disc , however each geostationary bird is just 1/10th of an arc second in size when viewed from Earth , and as far as I know , this type of picture has never been produced.

To simulate what it might look like , I have taken two actual photgraphs , and combined them.The result can be seen below.(The Astra group were imaged at night )

What surprises me is the "spread" of the birds across the solar disc , in this instance about 9 arc minutes (Sun is approximately 32 arc minutes across)

Mystery Bird ?

On the 21 February 2004 I managed to capture an interesting piece of video which shows an object moving near to the geostationary arc.In the region of 16 degrees east , it shows a geostationary satellite , with , near by what I first took as a second bird.However on close examination the second object is moving to the east.

So far there has been no positive identification , but thanks to some sterling work by SeeSat-L members it looks very much as if this is an old communications satellite , which has been de-commssioned and placed in a "Graveyard " orbit.
The other possibility (unlikely) is that it could be an asteroid.

To view the video (1.5mb) ,click .. here

The sequence is made up of eleven nine second frames (three frames were dropped ) covering a period of about two minutes.Estimated magnitude of the fainter object plus 12-14.

Update 24.2.04

Still no confirmed identity , but consensus of opinion is that the object is a geostationary bird either being moved into position , or re-positioned in the arc.This could suggest it is a classified military satellite.

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To have a look at how a much larger satellite in low earth orbit appears , when crossing the sun , follow the link above

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