Re: USA 129 (spectacular glint) & QuickSat: questions

Brian Hunter (bkh@chem.QueensU.CA)
Thu, 22 May 1997 09:47:01 -0400

By coincidence, I observed 96 72A Norad 24680 at 2:15 UT 1997 05 22 in
8/10th cloud. :-)  It was very bright (about 1st magnitude) and very fast. 
It was also 3 min 25 sec late according to the latest Molczan file.  I had
run a prediction for it but it was so late, I almost missed it and, as
usual these days, observing conditions were terrible.


Brian K. Hunter,                              Department of Chemistry
Professor                                        Queen's University                   Kingston, Ontario
(613)-545-2620                                Canada   K7L  4R6

44.236N 75.511W  70m

From: Bill Krosney <bkrosney@MBnet.MB.CA>
Subject: USA 129 (spectacular glint) & QuickSat: questions
Date: Thursday, May 22, 1997 3:18 AM

Was out observing Friday evening (May 17/97  UT) with a group of
students.  Thought Id impress them with a few satellite predictions.
I ran QuickSat against a Molczan tle file (cs970515) filtering for
satellites only brighter than 3rd magnitude.  I came up with a
handful of sats that with the bright twilight we were observing under
were less than impressive.

I was upstaged, and caught off-guard by a brilliant sat rising out of
the south around 03:35 UT.  Easily surpassed Mars in magnitude
(Mars is at 0.0) as it glinted for several seconds.  I took some good
natured ribbing for not being able to id the brightest satellite we saw.

Afterwards I ran the cs970515 Molczan file looking for a match.
Based on the time (to the nearest minute or two), and direction,
the only match I could find was for USA 129 (Norad 24680).

These were the elements (twenty-nine days old) from the Molczan 

USA 129         15.0  3.0  0.0  5.1 v
1 24680U 96072  A 97110.88696056 0.00017500  00000-0  18385-3 0    04
2 24680  97.8600 173.9660 0541000 132.5636 227.4363 14.74552770    09

Hoping to confirm this I had a similar pass (same time, and approx 
altitude and azimuth) for USA 129 last night (May 21/97 03:35 UT).
Unfortunately I had better than 9/10 cloud cover.  I was just about to
give up, turned off my time signal, thinking either I was wrong or
had missed it with the cloud cover when I glimpsed it through a hole.
Again it flared brighter than Mars for just under two seconds.  
Approximate altitude and azimuth when it flared was 40deg alt. and
190 deg. azi..  The sun at that time was at azi. 320 deg and alt. -10
Based on the above element set it was running about 3 to 3 and a half
minutes late.

Some questions:

I felt pretty sure this was USA 129.  Has anyone observed it recently
that the above elements are indeed running about 3 minutes or more slow?

Has anyone observed a bright glint from this sat before?

Is USA 129 in a sun-synchronous orbit, based on its inclination 
(>90 deg) and the fact that it repeated the same ground track almost
exactly 4 days later? 

QuickSat actually selected USA 129 on my short list of sats brighter
than 3rd magnitude.  Although I ignored it because it predicted a 
magnitude 18!  I can understand the errorneous magnitude prediction
because there is no base magnitude for 24680 in the quicksat.mag file.
But Im confused why it showed up in the short list.  Does QuickSat
ignore the magnitude filter if the satellite is not found in the 
magnitude file?

Ive got another good pass coming in a couple of days...if the clouds
will just clear!

As always...clear skies

(long. 97.27, lat. 49.85)