Re: Topex flare

Eberst (eberst@cableinet.co.uk)
Sat, 7 Mar 1998 19:19:56 +0100

At 16:54 98/03/07 +1000, Rob McNaught wrote:
>
>The positions from the camera will cover a longer arc than the time recorded
>by the video.  Peak magnitude from the video is around -3 (much brighter than
>Sirius and Canopus) and this is consistent with the trail on the photo.
>
>Using the alldat.tle file for 1998 day 058 gives only one candidate that
>fits the track excellently and is within seconds in time; 22076 TOPEX.
>Are flares from this object common?  Just what is it?

Yes, Topex does flare to the -3 magnitude.  It is usually referred to as 
Topex/Poseidon.  It's a European Space Agency  Geodetic satellite. It
has a large flat reflective base i.e. nadir pointing.  This means it will
flare when the following conditions are fulfilled: 
a. Its azimuth is the same as that of the Sun.
b. Its elevation above the horizon is equal to the depression of the Sun
   below the horizon.   
Example: A flare can be expected when the satellite is vertically above the
   Sun, at an elevation of x degrees, if the Sun is x degrees below the horizon.

I believe the Globalstar satellites are constructed with similar large flat
reflecting bases, so they should obey the same constraints for flares to occur?

So 'Iridflar' software could be joined by 'Topeflar' to give predictions of
these objects!
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best wishes  Russell  Eberst  @   North: 55 degrees, 56 minutes, 55 seconds
             West:  3 degrees, 8 minutes, 18 seconds: 
             43metres (150 feet) above sea-level

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