Iridium 27 'strobe' confirmed
Craig Cholar (3432P@VM1.CC.NPS.NAVY.MIL)
Fri, 02 Jan 98 18:52:56 PST
I just saw an evening SW -> W -> NW pass of Iridium 27 (24947 97-57D) and
witnessed the multiple flashes that were recently described by Jari
(finn@main.jetnet.ab.ca). I didn't expect to see anything, frankly,
but went outside in mostly cloudy skies to see what I could in between
the clouds. A gap appeared in the right place, and I was rewarded with
6 flashes, each separated by about 5 seconds, before it went behind some
clouds. It briefly reappeared about 30 seconds later, and saw another
sharp flash, but a bit dimmer. The brightest flashes were about -2.
The flashes were very short, lasting a fraction of a second, and
are nothing like the relatively long duration flares we've seeing.
Iridium 27 is non-operational, and is probably tumbling for it to be
able to flash like that. Thanks, Jari, for the report. I haven't
been looking at the dead Iridiums lately, but I will now! The other
Iridiums in non-operational orbits are 24842 and 24873. My notes
indicate that 24967 is also dead, but it appears to be in a useful
orbit based on perigee and apogee, so I may be mistaken.
Quicksat output:
*** 1998 Jan 3 Sat morning *** Times are UTC ***
H M S Tim Al Azi C Dir Mag Dys F Hgt Shd Rng EW Phs R A Dec
02 48 34 .0 43 278 C 92 20.8 1 5 566 310 796 km 1.3 113 2147 28.9
352 193 495 miles
Here are the Iridiums in non-operational orbits (excluding, of course,
the recently-launched ones that are still climbing):
Iridium 11 3.0 0.0 0.0 6.0 d 763 x 759 km
1 24842U 97030G 98002.26834903 .00000196 00000-0 56709-4 0 1475
2 24842 86.3993 79.0661 0003218 3.8618 356.2604 14.39254695 28485
Iridium 21 3.0 0.0 0.0 6.0 d 645 x 626 km
1 24873U 97034E 97364.79757766 .00000380 00000-0 48980-4 0 816
2 24873 86.3968 107.5212 0013550 4.8358 355.2992 14.77979544 25735
Iridium 27 3.0 0.0 0.0 6.0 d 559 x 552 km
1 24947U 97051D 98002.57785639 .00002579 00000-0 18572-3 0 986
2 24947 86.6369 14.5483 0005223 224.4997 135.5819 15.03755724 16626
Craig Cholar 3432P@VM1.CC.NPS.NAVY.MIL
Marina, California
36 41 10.3N, 121 48 17.9W (36.6862, -121.8050) UTC -8