Iridium 24 flare

Robert G Fenske Jr (
Mon, 22 Dec 1997 16:04:21 -0600 (CST)

On Sat, 20 Dec 1997, Jeff Hunt wrote:

> Observed my first (brighter than mag -4.5) predicted mag. -6.0 flare this 
> morning on Dec 20 at 11:21:48 UT (06:21:48 local) with the Sun at -10.6 

	I did this on Dec 18.  I was under a cloudless sky and pretty much
on the center line (reflection angle 0.02 deg) for Iridium 24.  It was
also had a high elevation of 67 deg and range of only 840 km.  It was
significantly brighter than Venus and had a noticeable halo around it.  I
don't feel I can adequately judge how bright it was without having
something to compare it against.  I would guess somewhere in the -8 to -10
range (though I know others have figured -9 is about the limit).  Two
things struck me as unusual about this event.  First is the more rapid--
compared to other flares I've seen--rise and fall of the brightness.
Second is that I perceived a discontinuous drop in brightness after
maximum.  I'm wondering if this was when the antenna quit the direct
reflection of the Sun and was left with just the specular reflection.

Robert Fenske, Jr.    Sw     |The Taming the C*sm*s series:
Southwest Research Institute            /R---\  |
Signal Exploitation & Geolocation Div  | I    | |"The Martian canals were the
San Antonio,Texas USA  ph:210-522-3931  \----/  | Martians' last ditch effort."