iridium 18, etc

richard.keen@kingsmarket.com
Tue, 02 Jun 98 23:44:35

                                    
 Hi all -
 Had a clear and mild night, a rarity up here at 2728 meters.
 I observed another pass of Iridium 18, for which the Quicksat prediction is
given below:
 1998 June 2  TueUT320 1037
 H  M  S Tim Al AziC Dir  Mag Dys F  Hgt Shd  Rng  R A  Dec Name
 5 43 47  .0 52 269C 267  6.6   5 1  481 103  591 1224 29.8 Iridium 18
 It gave off a rapid-fire sequence of 9 flashes in about 5 seconds very near
the culmination point listed above.  The flashes ramped up from magnitude +1
to -1, than back down to +1.  The flash sequence may have been cut short by
shadow entry.  Comparing this observation with another pass of Iridium 18 a
couple nights ago, there seems to be a pattern: the flashes occur near
culmination, over a period of several seconds.  There's a near-zenith pass
tonight, so I'll be out looking!
 
 Also saw TiPS in the 12-inch:
 6 12 25  .1 79  53C  87  6.3  15 4  657 192  667 1643 45.7 TiPS
 First sighted at culmination with the ends at magnitude 8 and the tether
nearly invisible.  As TiPS moved to the southeast, the ends faded as the
tether brightened, until just the tether was visible just before shadow entry.
 
 As twilight increased, I had no problem sighting TRMM at 1x, close to
predicted brightness at an observed magnitude +1.6.
 10 44 10  .2 30 176C 270  1.7   5 4  219 135  408 2041-20.2 TRMM
 
 Also saw the following high-flying objects, with Quicksat predictions:
 1998 Jun 2 UT
 Hr Min Alt Azi  Mag    Hgt    R  A    Dec  Range
 23230 ETS 6          94 56A    51 M 5.0 ELDY  7 M2   -1
 7  20   27 176 12.9  17716  17 15.4 -23.6  19609
 Observed 0720-0750, mag. 12, flsh 9, period 4.5s (40 flashes in 180s).
 
 22694 Galaxy 4       93 39A   127 M 3.5 ELDY  6 M2    0
 8  20   41 207 11.6  22431  16 40.4  -6.1  23642
 Possible sighting - a magnitude 12 object, not varying much over 10 minutes,
2.2 minutes of RA (about half a degree) east of the predicted position using
6-day old elsets.
 
 21533 Gorizont 23    91 46A   5.0 M 4.5 ELDY 10 M2   -1
 9  20   41 186 12.6  22493  18 43.1  -8.7  23664
 Observed 0920-0930, mag. 13, flsh 9, period 50s (6 periods in 300s); fainter
flashes at quarter period intervals.
 
 Cheers, Rich Keen
 Coal Creek Canyon, Colorado, USA (39.877 N, 105.391 W, elevation 2728m)