Iridium flare spectacular continues

Tue, 26 Aug 1997 07:57:59 -0500

Yesterday I reported on observations of bright flares from the latest
Iridium launch (24903-24907). After reviewing my video tape, I found
that all 5 satellites participated in the flare process. I would like to
correct the area of flare observability. The local elevation and
azimuths of that region were
elevation 35, azimuth 211, phase angles varied from 42 to 40 degrees. 

This morning, the same geometry recurred from Houston (26 October 1997
from 10:57:41 to 10:59:32) as the group passed through local elevation
34, azimuth 214 phase angle between 39 and 36 degrees. Again, a
spectacular performance! I attempted to carefully concentrate on the
maximum brilliance of each object and the time of rise and fade to
certain magnitude levels. As one object faded, another one generally

24907  reached -4 magnitude after rising from +4,then fading to +4 over
a 26 second interval
24906  reached +1, (rising from +2, fading to +2 over a 17 second
24905  reached -5 (rising from +4 then fading to +4 over 32 second
24904  reached -1 (rising from +2 then fading to +3 over a 22 second
24903  reached -4 (rising from +4 then fading to +4 over a 28 second

Keeping track of the details for all 5 was difficult, but as they spread
out it becomes easier until the geometry changes/the orbit is raised.
However, the narrow zone in the sky was quite repetitive. 
Tomorrow is Day 3. Will the flare festival continue?

I would like to speculate on the possible source of the brightenings.
The Iridium has two solar panels 130 x 46 inches in size, and 4 main
mission antennas (MMA) at 90 degrees to one another but canted at a 40
degree angle from vertical. I suspect the MMA could be the source. These
antennas are really flat panels 74 x 34 inches in size.

Paul D. Maley
DO5/Cargo Operations
NASA Johnson Space Center
Houston TX 77058 USA
phone: 281-244-0208
fax: 281-244-7622
latitude 29.5378 north; longitude 95.0868 west; altitude 6 m