Iridium 27 again

Ed Cannon (ecannon@mail.utexas.edu)
Mon, 20 Apr 1998 02:55:06 -0500

Mike McCants and I observed more brilliant flashes from Iridium 27 
on Sunday evening.  It was a pass quite low to our west, culminated
22 deg. alt. at 272 azi.  On two similar passes now (Thursday and
Sunday evenings) the brightest flashes have occurred in two 
different places before culmination.  Separately, both Saturday and 
Sunday it flashed very brightly quite a ways (a minute or more?) 
after culmination, but I'm not sure if it did that Thursday; I 
believe that we looked away at something else.

Iridium 27 apparently is rotating quite rapidly; I believe that Mike 
timed its flashes (something like bright/not bright/not bright) as 
occurring just over one second apart, or less than 4 seconds for the 
triple cycle.  The brightest flashes, though very fast, definitely
are of negative magnitude.

It appears that it may flash fairly reliably on low passes to the
west (i.e., poor phase angle) when it's on the descending node.  Has 
anyone seen if it flashes on near-zenith passes and/or low in the
east (i.e., good phase angle) on either descending or ascending node?  
(Actually, I was fairly sure that I unexpectedly saw one flash from 
it near the zenith several months ago but didn't have another chance 
or see any other messages about it for a while.)

I've been told that a group of about 200 people observed a -7 flare
from the visitor's center of McDonald Observatory!  I'm now looking
to see, in the near future, an Iridium flare shown on television.

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