Observed PREDICTED Monster Iridium Flare

Ron Lee (ronlee@pcisys.net)
Sun, 05 Oct 1997 06:26:40

Rob Matson predicted an off-specular angle of 0.1 for the 
Iridium 6 pass on 5 Oct 97 local in the morning. It was a northbound,
high elevation pass, with the flare near Polaris.  As some may
recall, I was originally skeptical that these flares would occur,
but every one has.   

I set up my camera for this one, expected max flare at about 11:51:30
UT.   I saw it about 30 seconds early...dim at first...then it flared up
quickly to the brightest satellite I have ever seen.   Looking at
Sirius afterwards...Sirius looked DIM in comparison.  I determined the
time to be 11:51:45 UT for max flare, realizing that 15 seconds late
is not bad when the mirrors can be off a bit from the "standard"
orientation.   Then I verified the predicted time and it was 11:51:45 UT!

NORAD   date    time   Dir aF eF aM  eM aS   eS Phs Dur Mag Obs COSPAR
xxxxx dd-mm-yy hh:mm:ss x xxx xx xxx xx xxx -xx xxx tt Sn III yynnnp
24794 97-10-05 11:51:45 N 007 36 092 83 085 -14 089 06 -6 RGL

I put the flare magnitude at -6 because I have no way to know exactly.
It was greatly brighter than Sirius.     Other recently observed flares
are below.    Note on #24840 and #24836 a preflare before the predicted
flare. This phenomenon was earlier reported by Leo Barhorst (and maybe
Jake Rees).   In the flare report header, I changed aI and eI to 
aF and eF, where F equals FLARE.  the "I" for "Iridium" had caused
some confusion.

The neat thing about all these flares are that they were predicted....
in this case by Rob Maston.   Accuracy of flare time and correlation
of off-specular angle to observed magnitude were excellent.  Very
impressive.  The question I have include why dis #24840/24836 show
a multiple flare...and which mirror is causing the glare on the northbound
passes near Polaris?


24837 97-09-30 01:56:31 S 149 55 086 71 279 -15 125 05 +0 RGL
24841 97-10-01 01:50:33 S 147 54 087 71 277 -13 124 xx -2 RGL
24795 97-10-01 12:15:25 N 004 46 094 88 087 -09 092 xx +2 RGL
24792 97-10-02 12:09:25 N 005 45 095 87 087 -10 092 xx +2 RGL
24839 97-10-03 01:38:30 S 147 51 086 69 275 -12 123 15 +0 RGL
24840 97-10-04 01:32:05 S 137 58 086 68 273 -11 124 04 +1 RGL
24840 97-10-04 01:32:35 S 149 48 086 68 273 -11 121 15 +3 RGL
24836 97-10-04 01:41:20 S 167 59 087 83 275 -12 111 03 +2 RGL
24836 97-10-04 01:41.9  S 171 48 087 83 275 -12 110 xx +4 RGL

Ron Lee