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Cloud around Spot 1

The following is an edited version of a discussion on SeeSat-L. It was triggered by an 'unknown' observation of a cloud around a satellite. The original observation has not been identified, but David Bishop subsequently reported about an old observation he had made in 1991. Here we go :

David Bishop

I had to go back three notebooks to find this observation. That was over 250 unique satellite observations ago, not to mention about 500 galaxies and 15 comets. Here are my notes from that evening:

7/16/91

Something strange. At 10:06 EDT I noticed a cloud due east. This was odd as that part of the sky was cloudless. I put my binoculars on it and notice a fairly bright (mag 3) satellite in the center of it. As the satellite moved across the sky, so did the cloud. I picked it up at an elevation of about 40 deg at Az 90, and followed it to Az 30.

Added Later: Cosmos 2100 r?

From my own memory: The cloud was not even, there were portions of it which were brighter and some darker. The satellite was in the center and the densest part of the cloud. The cloud was denser to the upper left of the satellite and less dense to the lower right. Rotation period was about 2.5 / second (with a wide margin for error as I didn't time it). It was about 10 degrees up when I lost it in the trees.

Mike McCants

The object "Spot 1" appears to be the best candidate:

Ted's file of 91/07/13:
1 16613U 86019  A 91193.14231257 -.00000106  00000-0 -41034-4 0  3796
2 16613  98.6965 266.6727 0001802 122.1925 237.8866 14.20069262119273
Ted's file of 91/07/20:
1 16613U 86019  A 91199.69527776 -.00003985  00000-0 -18754-2 0  3841
2 16613  98.6907 273.1056 0002135 118.1354 242.0005 14.20017033120205

Note that five element sets were issued in a 6 day period, the mean motion is lower and the drag term is negative.

Some time prior to 91199, Spot 1 manuevered into a slightly higher orbit. 91/199 is July 18.

Predictions for July 16 for David using 91199 elset:

16613 Spot 1         4.7 1.8 1.8  RadarCrossSection=24
 H  M  S  Al  Az  Dir  Mag Dys F  Hgt  Rng Phs
 9 58  6  20 109  298  5.5  -2 8  518 1134  26
 9 58 56  25  99  291  5.1  -2 8  518 1013  36
 9 59 47  29  85  282  5.0  -2 8  518  929  49
10  0 37  30  68C 272  5.0  -2 8  518  894  64
10  1 28  29  51  260  5.3  -2 8  518  913  79
10  2 18  26  36  251  5.7  -2 8  518  984  93
10  2 43  24  30  247  5.9  -2 8  518 1035  99
So, my guess is that the cloud around it was due to RCS jet firings.

David Bishop and Mike McCants, some editing done by BDP



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Next: Molniya flasher identified Up: Flash 93 Previous: Update on the



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