RE: SATOBS ML (4353), 31 May 2014: USA 161

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Sat, 31 May 2014 09:41:57 -0400
Marco Langbroek reported the following observations, which resulted from a planar search:

26934 01 044A   4353 G 20140531013002250 17 75 2022511+420150 56  +020 10
26934 01 044A   4353 G 20140531013012300 17 75 2031398+513440 56  +020 10
26934 01 044A   4353 G 20140531013022250 17 75 2045513+608860 56  +000 10
26934 01 044A   4353 G 20140531013032300 17 75 2110170+696990 56  +010 10

Marco commented:

> With Leo's first post winter-blackout obs from a week ago (May 24) this obs
> should constrain the current orbit much better.

Marco does seem to have found 01044A, but his observations correlate with Björn Gimle's UNID of Apr 22 (obs below), that
Björn suspected was 01044A. Until now, I had rejected that hypothesis. 

00000 14 612A   5919 E 20140422003614000 18 25 1402950+341689 55 S
00000 12 612A   5919 E 20140422003641000 18 25 1224356+521941 55 S
00000 12 612A   5919 E 20140422003648000 38 25 1201370+543641 55 S
00000 12 612A   5919 E 20140422003715000 18 25 0924699+595807 55 S
00000 12 612A   5919 E 20140422003725000 18 25 0838636+590516 55 S

I have obtained the following approximate solution to Björn's and Marco's observations:

USA 161                                                  411 X 425 km
1 26934U 01044A   14151.05316463  .00007977  00000-0  15000-3 0    05
2 26934  97.5160 287.4274 0010499 298.2537  61.7653 15.48511235    00
Arc 20140422.03-0531.06 WRMS resid 0.055 totl 0.010 xtrk

Mean motion and rate of decay are the least certain elements, but predictions should be accurate to ~1 min. of time for
the next few nights.

When last observed by our group, in 2013, 01044A had been near sun-synch, in a ~97.0 deg, ~15.595 rev/d orbit. The above
orbit is somewhat more retrograde than sun-synch, and precesses at about 1.04 deg/d. It would have been coplanar with
our last 2013 orbit of 01044A around March 2014.

One of Leo Barhorst's UNIDs of May 24 was very close to 01044A's 2013 plane, so it was reasonable to suspect that it was
that object; however, it was a brief observation (~8 s). Björn and Marco observed for 71 s and 30 s respectively; both
reported a bright object, which Marco observed to flare brilliantly, a common KeyHole behaviour. 

Unless I have overlooked some other currently lost object in a secret orbit, it seems likely that the above elements are
of 01044A. I claim no infallibility in these matters, so independent review would be prudent and welcome.

Ted Molczan



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Received on Sat May 31 2014 - 08:42:50 UTC

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