irregular iridium 18 and other stuff

richard.keen@kingsmarket.com
Sun, 31 May 98 14:49:45

                                  
 Hi all -
 I observed four passes by irregular Iridia satellites (those not in the
standard operational orbits), along with a few other interesting objects, with
the following results (first, the Quicksat predictions; heights and ranges in
miles):
 
 1998 May 31  Sun  UT  319 1038
 1998  Coal Creek Canyon, CO 2000 15.0 15 F F T T F
 H  M  S  Al AziC Dir  Mag Dys F  Hgt Shd  Rng  R A  Dec Name
 4  7  3  34 272C 268  7.8   3 2  474 403  764  925 22.5 Iridium 11
 Two flashes to mag. 0 at 04:06:00, while in the northeast sky.
 4 50 27  82  85C  87  5.5   3 9  394  88  397 15 3 40.0 Iridium 21
 One flash to mag. 2 at culmination, just before shadow entry.
 5 10 42  58  82C  87  6.2   3 1  481  83  557 1728 36.6 Iridium 18
 Five quick flashes to mag. 0 at 05:10:30, near culmination, all within 2
seconds (i.e., 2 flashes/second).
 5 45 15  66 268C 267  6.2   3 2  480  61  520 1319 34.8 Iridium 42
 First saw at mag. 5 in the bowl of the Big Dipper, then a slow fade to
invisibility at 1x, then return to mag. 5, then shadow entry.  About 1 minute
between brightness peaks.
 So, it looks like Iridium 18 has joined the likes of 11, 21, and 27.
 
 Also, an observation of the Swedish Viking satellite:
 3 32 52  76  71C 275 11.0   3 8 46474495 4715 1420 42.8 Viking 16614=86-19B
 Observed 0332-0344, mag. 12-13, brighten unsteadily to mag. 12, then sudden
fade back to mag. 13, this pattern repeating every 8 seconds.  A few flashes
to mag. 11 towards end of observation, as object sank in the north.
 
 And, good old TiPS passed almost overhead:
 6 42 38  81  53C  87  6.2  13 4  657 150  665 1658 44.9 TiPS
 Obs. with 12" at 33x, "Ralph" and "Norton" at the ends of the tether were
mostly mag. 8-9, with occasional slow flashes to magnitude 7.
 
 Finally, the International Ultraviolet Explorer, which looked much the same
as the last time I observed it.  Here's the Highfly output:
 1998 May 26 UT
 10637 IUE  78 12A  7.5 M 3.5 ELDY 14 M2  0
 H  M   Al Azi  Mag   Hgt     RA     Dec   Range
 6 15   64 239 11.4  19918  13 49.2  23.4  20267
 6 45   61 230 11.4  20345  14 24.6  18.6  20769
 7 15   57 224 11.4  20802  14 56.3  13.6  21346
 Observed 0630-0705, mag. 13 with flashes to mag. 12.  Flash pattern: fffx,
i.e., 3 flashes then a missing one.  Timed 28 cycles/122s = 4.36s period (or
about 1.1 seconds between flashes).  Kurt: I'm sending the obs in PPAS format
separately.
 Cheers, Rich Keen
 Coal Creek Canyon, Colorado, USA (39.877 N, 105.391 W, elevation 2728m)