RE: Foton 12 R/B
Ted Molczan (molczan@home.com)
Sat, 25 Sep 1999 12:43:36 -0400
I too would have expected the object to have been glowing at a lower altitude
than the approximately 138 km given by the predicted elements for the epoch of
Mike DiMuzio's observation. One question that arises is just how high can an
object be and still glow due to heating on contact with the upper atmosphere?
Desmond King-Hele commented in Observing Earth Satellites, that satellites
begin to glow at a height of about 90 km. I imagine that the exact height
depends on the object's orbital velocity and the local atmospheric density at
perigee.
The only other case of high-altitude glowing I recall, was an observation by
Steve Bolton of what he thought might have been the final decay of Raduga 33 r,
on 20 Aug 96 UTC:
http://www2.satellite.eu.org/seesat/Aug-1996/0151.html
In fact, at the time of his observation, the object's apogee was still over
1800 km, and it did not decay until 21 Aug. It turned out that Bolton had the
good fortune to see it near perigee, about 100 km. Apparently, it was glowing
brightly during each pass near perigee:
http://www2.satellite.eu.org/seesat/Aug-1996/0153.html
Note that in my above post, I mis-typed Steve Bolton's longitude:
"Below is an ephemeris for Saint John N.B. (45.28 N, 60.05 W):"
should have been:
"Below is an ephemeris for Saint John N.B. (45.28 N, 66.05 W):"
I have since found an official NORAD elset, that is reasonably close to the
epoch of Bolton's observation, which occurred at about 96233.03264 (if anyone
has any closer official elsets, please post them):
1 23797U 96010D 96233.24950077 .54585672 30314-4 12533-2 0 3101
2 23797 47.8008 201.2704 1459706 74.9309 300.8107 13.15295436 5404
This confirms that the object was slightly more than 100 km above the Earth
when observed by Bolton. Note that the altitude calculated by my ephemeris
generator is relative to the actual sub-satellite Earth radius.
20/ 8/96 00:00 - 04:00 UTC J2000.0 EL > 1 Steve Bolton
Raduga 33 r 96010D 23797 Bull = 310
SGP4 Age = -0.2 d Unc = 87 s ( 50%)
Offset = 0.00 min
TIME %I Mv AZ EL R.A. DEC FE VANG RANGE ALT
-------- -- ---- --- -- -------- --------- -- ---- ----- -----
00:44:30 12 7.7 263 0 12:35:55 -04:19:53 7 0.09 1104 106
00:45:54 UMBRA 274 10 12:33:41 11:12:45 8 0.43 449 100
00:46:12 UMBRA 283 16 12:27:17 21:33:21 8 0.82 320 100
00:46:21 UMBRA 291 21 12:20:16 30:12:39 8 1.22 262 101
00:46:27 UMBRA 299 25 12:12:08 38:12:12 8 1.61 228 101
00:46:32 UMBRA 308 28 12:00:53 46:39:15 8 2.00 205 101
00:46:36 UMBRA 317 31 11:45:55 54:40:44 8 2.33 189 101
00:46:39 UMBRA 325 33 11:27:36 61:19:09 9 2.55 181 101
00:46:42 UMBRA 334 34 10:56:37 68:11:30 9 2.71 176 102
00:46:45 UMBRA 344 35 09:57:20 74:37:54 9 2.78 174 102
00:46:48 UMBRA 354 34 07:57:04 78:58:23 9 2.74 175 102
00:46:51 UMBRA 3 33 05:15:25 78:32:47 9 2.61 179 102
00:46:54 UMBRA 12 32 03:34:09 74:15:36 9 2.41 187 102
00:46:57 UMBRA 19 30 02:44:38 68:55:04 10 2.17 197 103
00:47:00 UMBRA 25 28 02:17:53 63:40:31 10 1.92 210 103
00:47:04 UMBRA 32 25 01:57:34 57:23:01 10 1.62 229 103
00:47:09 UMBRA 39 22 01:43:15 50:47:50 10 1.29 257 104
00:47:15 UMBRA 45 19 01:33:22 44:32:17 10 0.99 295 105
00:47:23 UMBRA 51 16 01:25:49 38:16:53 10 0.71 349 106
00:47:34 UMBRA 56 12 01:20:13 32:14:34 10 0.48 428 107
00:47:50 UMBRA 61 9 01:16:18 26:29:32 10 0.30 548 109
00:48:15 UMBRA 65 5 01:14:11 21:02:19 10 0.18 741 114
00:48:57 UMBRA 69 1 01:14:28 15:50:56 11 0.10 1072 124
Of course, this does not answer the question of exactly what height produced
the glowing. It could have started glowing well above 100 km.
Ted Molczan