USA 129 (spectacular glint) & QuickSat: questions

Bill Krosney (bkrosney@MBnet.MB.CA)
Thu, 22 May 1997 00:18:35 -0700

Was out observing Friday evening (May 17/97  UT) with a group of
students.  Thought I=92d 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=20
file:

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=20
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. =20
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
deg.
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
such
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=20
(>90 deg) and the fact that it repeated the same ground track almost
exactly 4 days later?=20

QuickSat actually selected USA 129 on my short list of sats brighter
than 3rd magnitude.  Although I ignored it because it predicted a=20
magnitude 18!  I can understand the errorneous magnitude prediction
because there is no base magnitude for 24680 in the quicksat.mag file.
But I=92m confused why it showed up in the short list.  Does QuickSat
ignore the magnitude filter if the satellite is not found in the=20
magnitude file?

I=92ve got another good pass coming in a couple of days...if the clouds
will just clear!

As always...clear skies

Bill
(long. 97.27, lat. 49.85)