Fascinating: 92-8B, 70-25CD (long)

Jim Varney (sat_watcher@rocketmail.com)
Sun, 10 Aug 1997 10:27:47 -0700 (PDT)

Observed two interesting objects:

COSMOS 2180 r, 92 8B, 21876.  This Kosmos (SL-8) booster is a nice
flasher with period of 6.3 seconds.  An easy object to observe, it
makes a great object for anyone who might want to try flash period
observing for the first time.  What makes 92 8B interesting is the
satellite's tumbling history.  From the PPAS database:

   Object, yy-mm-dd, UT, Observer, Flash period
   92-  8 B 92-11-26 16:52      LB     Steady  
   92-  8 B 93-04-28 21:16      TC      28.42  
   92-  8 B 93-08-17 20:40      DC     132
   92-  8 B 95-08-02 22:14      LB       8.59  
   92-  8 B 96-10-16 20:48      RE      20
   92-  8 B 97-03-09 02:55      BD       2.57
   92-  8 B 97-08-09 05:17      JEV      6.3

As you can see, 92 8B has had at least three tumbling rate
accelerations since it has been in orbit.  My observation shows it to
be gradually slowing down as tumbling boosters normally do.  Will it
accelerate again?

NIMBUS 4 r CD, 70- 25CD, 4719.  Craig Cholar sent a note that I was
going to have a visible pass.  I'm glad he did -- not only is it
interesting to observe, the object has quite a history.

This is one of many pieces of space junk that used to be part of an
Agena D booster.  The "History of Satellite Fragmentations" document
reports that the Agena initially exploded on Oct. 17, 1970, at 0317
UT.  This Agena had a habit of not completely blowing itself apart as
it underwent additional explosions two times in 1985, again in 1986
and finally in 1991.

The PPAS database lists an observation of the CD fragment by Russell
Eberst in Oct 1972 as having a flash period of a mere 0.1 second. 
What a sight that must have been!  Interestingly, this fragment has
had some minor accelerations as well.  In 1980 "BK" saw it with a
flash period of 5.06 seconds.  It was not observed again (at least not
reported, anyway) for 16 years until Mr. Eberst saw it again with a
period of one second.  I observed it last night at 1.70 seconds:

70- 25CD 97-08-10 05:26      JEV  61.2 0.1  36  1.70  FF, mag 4->inv

Very sharp, short flashes with the satellite completely invisible
between them.

The PPAS database also has reported observations for other pieces of
the Agena.  70- 25 N, 70- 25 R, 70- 25 S, 70- 25 V, 70- 25 W, 70- 25
Y, 70- 25AZ, 70- 25BF, 70- 25BW are all listed as having been seen in
the past.  If any of the long-time observers or the space analysts
have any insights or recollections about the Nimbus 4 incident, please
share your thoughts.

It would be interesting to observe these and other fragments to see
what they are up to.  You have a lot to choose from.  There are 272
cataloged objects still in orbit according to the Satellite Situation
Report, 86 of which have a radar cross section of 0.1 sq m or larger
and thus are potentially visible.

Jim Varney   121.398W  38.458N 8m   Sacramento, CA
jamesv@softcom.net, sat_watcher@rocketmail.com

Galileo: the original ATM

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