New (Old?) Flasher?

Ed Cannon (ecannon@mail.utexas.edu)
Fri, 29 Aug 1997 06:55:05 -0500

Wednesday night while Mike McCants and I were tracking Iridium 4 
(97-20E/27496 -- no flash), another one appeared in the field going 
the opposite direction, and we followed it.  In a few seconds Mike 
said, "Is that thing flashing at us?"  It was, and he timed the 
period at 1.9 seconds.  I've just spent some hours trying to ID the 
object with alldat.tle and molczan.tle elements, and the best 
candidate I've found is 73-86CD:

  30.314  97.866  920.   BCRC, Austin, Texas      2000  9.9 20 F F T T T

***  1997 Aug  27  Wed evening  *** Times are PM CDT  ***  2044  621

 H  M  S  Tim Azi Al C Dir  Mag Dys F  Hgt Shd  Rng  EW Phs  R A   Dec 

07085               73 86CD   
10  6 55   .0 226 35    65 22.7   0 4  934 612 1389  .7  86 1635 -11.9 
10  6 57   .0 226 35    65 22.7   0 4  934 613 1386  .7  86 1634 -11.6 
10  6 59   .0 226 35    65 22.7   0 4  934 614 1384  .7  86 1634 -11.4 
10  7  0   .0 226 36    66 22.7   0 4  934 616 1382  .7  86 1633 -11.1 

24796 Iridium 4      97 20E                        
10  6 55   .0 225 37   233 21.3   0 9  484  97  736 1.2  84 1641 -10.4 
10  6 57   .0 225 37   232 21.3   0 9  484  95  740 1.2  84 1641 -10.9 
10  6 59   .0 224 37   232 21.3   0 9  484  94  744 1.2  84 1642 -11.4 

Here are the 73-86CD elements for the above predictions:

07085
1 07085U 73086CD  97240.04563599 -.00000031 +00000-0 +10000-3 0 07972
2 07085 102.1722 279.5789 0095866 227.6880 131.6047 12.57993746092210

The July 1997 SSR says the RCS of 73-86CD is 0.11.  I'm very skeptical 
that such a small object at a range of almost 1400 miles (2240 km) could 
have been the flasher we saw -- but I didn't find a better candidate.  
I noticed in the online flash database some reports in 1975 for 73-86DC 
(07138, RCS=0.62), another fragment from the same bunch of Delta 1 debris 
objects.

For what it's worth, the second-best candidate was 65-48N/21945, a Transit
5B-6 debris object with an RCS of 0.003!

Ed Cannon
Austin, Texas, USA
30.3086N, 97.7279W, 165m