Flaring Geosat Season

From: Ed Cannon (ecannon@mail.utexas.edu)
Date: Sun Sep 02 2001 - 18:56:16 EDT

This is a reminder that "Flaring Geosat Season" is approaching!  

For new folks, around the equinoxes operational geostationary 
satellites can brighten to much brighter magnitudes than usual, 
so that they can be much easier to observe.  Along with the 
seasonality, the phenomenon is latitude-dependent as well.  
Here's slightly adapted version of a table of suggested 
optimum dates for various latitudes originally published by 
Rainer Kresken:

latitude    optimum date
-80         01 September
-60         04 September
-40         09 September
-20         15 September
0           23 September
+20         30 September
+40         07 October
+60         12 October
+80         15 October

Rainer's original, very informative message on the topic is
at this location:


Last year about the end of September and into early October I 
was able to see several of them for a number of consecutive 
evenings using only my 10x50 binoculars.  What I learned was 
to look at two or three easily recognizable asterisms at the 
correct declination.  I use Highfly for geosat/near-geosynch
satellite predictions.

One note I would add is that, apparently due to tolerances 
allowed for pointing of solar panels, the constraints on when 
the satellites can flare are somewhat flexible.  Ones that 
are very accurately pointed at the Sun might flare according 
to very strict time constraints just near shadow entry and 
exit, but those that are more "off" from exact solar pointing 
can flare earlier and/or later than they "should" if they were 
more accurately pointed.  I found last year that I could see 
them across quite a large expanse of the sky on each of the

A second note is that there are some operational ones that are 
not at zero inclination, and I believe that they can flare a 
somewhat different times due to that fact as well.

There's more information on this page of Jason Hatton's site 
in the section called "Operational geosats":


See also the paragraph about "beaming" on the VSOHP page about 


Ed Cannon - ecannon@mail.utexas.edu - Austin, Texas, USA

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