RE: raduga decay
Ted Molczan (molczan@fox.nstn.ca)
Tue, 20 Aug 1996 15:35:40 -0400
Steve Bolton wrote:
>Having observed decay of Raduga 33 SL r2, some questions arise. This is the
>first decay I've seen.
I believe that most likely you did not see decay, but
arguably something as good or better. The object was
virtually at perigee when you observed, and probably
was experiencing a great deal of heating because it
was so low - about 100 km. I reached this conclusion
based upon the following Alan Pickup elset, posted to
Seesat-L yesterday:
Raduga 33 SL-12 r2
1 23797U 96010D 96233.01776407 .97557836 28856+0 16460-2 0 92774
2 23797 47.6011 201.6498 1165766 74.4749 298.0744 13.84811729 5380
The epoch was 00.25 UTC on 20 Aug 96, only minutes prior to your
obs. Based on the SGP model, and assuming 6371 km for the Earth's
radius, its perigee and apogee would have been about 100 km and 1807 km,
respectively, so I very much doubt it was decaying, but read on.
Below is an ephemeris for Saint John N.B. (45.28 N, 66.05 W):
20/ 8/96 00:00 - 01:00 UTC J2000.0 EL > 1 Steve Bolton
Raduga 33 r 99996A 99996 Bull = %9277
SGP4 Age = 0.0 d Unc = 0 s ( 50%)
Offset = 0.00 min
TIME %I Mv AZ EL R.A. DEC FE VANG RANGE ALT
-------- -- ---- --- -- ----- ----- -- ---- ----- -----
00:41:46 13 7.2 261 0 12:38 -5.4 7 0.08 1120 109
00:43:17 11 5.2 272 12 12:43 10.7 8 0.43 421 105
00:43:34 SHADOW 280 19 12:41 20.7 8 0.83 301 105
00:43:43 SHADOW 288 24 12:39 29.7 8 1.26 243 105
00:43:49 SHADOW 296 29 12:37 38.2 8 1.70 209 106
00:43:53 SHADOW 303 33 12:34 45.5 8 2.06 190 106
00:43:57 SHADOW 313 36 12:29 54.1 8 2.45 174 106
00:44:00 SHADOW 322 39 12:22 61.6 8 2.72 165 106
00:44:03 SHADOW 332 41 12:09 69.6 9 2.92 160 106
00:44:06 SHADOW 343 42 11:38 77.9 9 3.01 157 107
00:44:08 SHADOW 351 41 10:36 83.2 9 3.00 158 107
00:44:11 SHADOW 2 40 04:24 85.3 9 2.87 161 107
00:44:14 SHADOW 12 38 02:08 78.6 10 2.65 168 107
00:44:17 SHADOW 21 36 01:38 71.6 10 2.37 178 107
00:44:20 SHADOW 28 33 01:25 65.3 10 2.09 190 107
00:44:24 SHADOW 36 30 01:17 58.1 10 1.73 209 108
00:44:28 SHADOW 41 26 01:12 52.2 10 1.42 231 108
00:44:33 SHADOW 47 23 01:09 46.2 10 1.12 261 108
00:44:40 SHADOW 52 19 01:07 39.8 10 0.82 307 109
00:44:49 SHADOW 57 15 01:05 34.0 10 0.57 370 110
00:45:02 SHADOW 61 11 01:04 28.3 10 0.37 465 111
00:45:22 SHADOW 65 7 01:05 22.8 11 0.22 616 114
00:45:55 SHADOW 68 3 01:06 17.6 11 0.13 869 119
00:46:54 SHADOW 71 0 01:11 12.5 11 0.07 1327 131
The above is about 3 minutes earlier than your observed time, and it just
misses the bowl of the Big Dipper, which represents excellent accuracy
on Alan Pickup's part, given the incredibly high rate of decay.
The following ephemeris allows for the Earth's rotation during the three
minutes of prediction error:
TIME %I Mv AZ EL R.A. DEC FE VANG RANGE ALT
-------- -- ---- --- -- ----- ----- -- ---- ----- -----
00:44:54 13 7.2 263 0 12:37 -4.4 7 0.09 1116 108
00:46:22 SHADOW 274 11 12:39 11.3 8 0.42 442 105
00:46:40 SHADOW 282 18 12:35 21.6 8 0.81 315 105
00:46:49 SHADOW 290 23 12:31 30.1 8 1.20 258 106
00:46:55 SHADOW 297 27 12:26 38.1 8 1.58 224 106
00:47:00 SHADOW 306 31 12:19 46.6 8 1.98 200 106
00:47:04 SHADOW 315 34 12:10 54.8 8 2.32 185 106
00:47:07 SHADOW 323 36 11:58 61.6 8 2.55 176 107
00:47:10 SHADOW 333 38 11:37 69.0 9 2.73 171 107
00:47:13 SHADOW 343 38 10:52 76.3 9 2.81 168 107
00:47:16 SHADOW 353 38 08:47 82.2 9 2.79 169 107
00:47:19 SHADOW 3 37 04:46 82.0 9 2.67 173 107
00:47:22 SHADOW 12 35 02:52 76.6 10 2.47 180 108
00:47:25 SHADOW 20 33 02:10 70.5 10 2.23 190 108
00:47:28 SHADOW 27 31 01:50 64.8 10 1.97 202 108
00:47:32 SHADOW 34 28 01:36 58.1 10 1.65 221 108
00:47:37 SHADOW 41 24 01:27 51.2 10 1.32 248 109
00:47:43 SHADOW 47 21 01:20 44.7 10 1.01 285 109
00:47:50 SHADOW 52 17 01:16 38.9 10 0.75 331 110
00:48:00 SHADOW 57 14 01:13 33.0 10 0.52 401 111
00:48:14 SHADOW 61 10 01:10 27.4 10 0.34 503 113
00:48:36 SHADOW 65 6 01:10 21.9 10 0.20 669 116
00:49:13 SHADOW 69 3 01:11 16.6 11 0.11 954 122
00:50:19 SHADOW 72 -1 01:15 11.4 11 0.06 1465 137
Having corrected for Earth's rotation, the above places the object
well inside the bowl of the Big Dipper moments after 00:47 UTC.
But most important - the object was in shadow! So you could only have
seen it because it was glowing! Of course in your earlier message
you stated:
>Through binoculars a 3-4 degree trail was visible.
which indicates that it was also losing some mass!
>Questions.
>1. This event should have been widly observed from central Canada and NE US.
> Any other posts/ sightings ?
The glowing probably was confined to very near the perigee, and you
had a ring-side seat. Given the bright twilight, casual observers
probably would have missed it.
>2. If the STSPLUS plots are correct, this object survived a very low pass on
>the rev prior . Possible?- or is STSPLUS not reliable.
Yes it did. I believe that STSPLUS uses the older SGP model, instead
of the current SGP4 model. SGP produces nearly identical results to
SGP4, except under conditions of extreme drag.
>3. If it did survive the pass on rev 538- might the dimming I observed
>represent the sat climbing out of dense atmosphere again? Raduga's next pass
>was not attempted by me- but was favorible for N. A. observers.
I guess no other SeeSaters were looking.
>Finally, for those not lucky enough to see a decay, keep trying -it is spectacular
Well, I am not certain that it will survive until tonight,
but here is the latest of Alan Pickup's excellent elsets:
Raduga 33 SL-12 r2
1 23797U 96010D 96233.29966095 1.31849363 55988+0 18869-2 0 92777
2 23797 47.5783 200.3952 0896799 75.6602 294.1224 14.48531738 5428
Clear skies!
Ted Molczan