Satgen258  Satellite Spotter Part 6  by GM4IHJ               5th Mar 94
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Azimuth and Elevation changes. Satellites in LEO low earth orbit below
1600 kms, move fast. If you have a directional beam antenna, you should be
able to quickly decide whether your unknown signal is moving or not. This
movement can be even more pronounced if your antenna can be moved in
elevation as well as azimuth.

A careful check of a moving signal can sometimes establish which side of
the Pole the satellite passes. Sats with orbital inclination less than 90
degrees are most often of Russian origin, going to the right hand,east of
the North pole as they ascend in latitude, and coming from the left side
west of the North pole as they descend towards the Equator. By contrast
most American satellites have orbital inclination greater than 90 degrees
, and. therefore take the opposite routes ascending left west of the pole
and descending right east of the north pole. Satellite watchers in the
southern hemisphere will find that they need to reverse the above rules in
respect of passages round the South pole.

High altitude long range elliptical orbiters have a totally different
apparent motion. They hardly move at all when out near their apogee high
point, but after apogee as they swing down towards perigee low point their
motion becomes obvious and can be as fast as a direct orbit LEO sat. High
altitude orbiters are almost always in orbits of inclination less than 90
degrees.

Less obvious movers are the high altitude circular orbiters. They move
much more regularly albeit slowly when compared with LEO sats.

Geostationary satellites do not appear to move at all. But they are always
positioned on your geostationary arc which varies in elevation ,
maximising for geosats due south of your station " on your meridian" and
declining to zero elevation for geosats 75 degrees of longitude either
side of your meridian. The interesting exceptions to this are the
geosynchronous sats. They have a 24 hour orbit period but their orbit is
inclined to the Equator sometimes as much as 20 or 30 degrees ( unlike the
geostationary which has zero orbital inclination). In consequence of this
orbital inclination the geosynchronous satellites move north of the
geostationary arc for half the day then goes south of it for the rest of
the day. A feature which is useful for an intelligence gathering satellite
which moves say - directly over China during their local day, then 6 to 8
hours later is further west overhead Russia for several hours befor
 swinging south of the Equator for the rest of the day. This latter trick
might be the best way to share a satellite in the geostationary orbit
between two separate radio amateur communities Eg Europe Africa in their
day and, North and South America in their day. The venerable old
geosynchronous satellite Ultra Violet Explorer provided just this sort of
service to European and then American Universities each day.

Summary.  All satellites display peculiarities of azimuth and elevation.
The actual pattern depends on their orbit parameters. If you recognise the
pattern , it helps classify the satellite type. 73 de John GM4IHJ@GB7SAN