Ed Cannon (
Mon, 15 Feb 1999 03:54:18 -0600

It seems that NOAA 15 (25338, 98-30A; called NOAA K prior to 
its launch) is fairly reliable in displaying a couple of 
unusual phenomena.  On high evening passes east of the zenith, 
it fairly often exhibits a quick, bright flash.  On some of 
its current high evening passes, as it descends to the north 
long after culmination, it can flare to as bright as negative 
magnitudes for quite a few seconds.  So I went looking for 
more information.  There's a labeled line drawing of it at 
this location:

Below that are details regarding its configuration.  Its solar 
array is 6.15 by 2.73 meters (section -- a pretty 
good-sized reflector.  But in the drawing, it also has 
something called a "deployable solar shield" that looks like 
a fair-sized flat surface.  The satellite also appears to have 
several other smaller flat surfaces here and there.

Since it's an operational, 3-axis stabilized object, the 
unusual phenomena that NOAA 15 (and presumably the next two, 
currently known as NOAA L and M) displays may be predictable.

Randy John mentions in his SkySat documentation, "This program 
has been released to allow people to try to predict IRIDIUM 
(and other satellite) flares."  Has anyone tried to use Skysat
to predict flares from other objects?  I think that NOAA 15 
may be a good candidate.  (USA 81 may be also, in terms of 
predicting its sparkling phase.)

Ed Cannon - - Austin, Texas, USA