RE: NROL 129 search elements

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Thu, 30 Jul 2020 12:23:49 -0400
Leo Barhorst has observed the NROL-129 suspect in one of the two search orbits I posted on July 28.

His observations are here:

http://satobs.org/seesat/Jul-2020/0154.html

79395 20 711A   0796 E 20200729222735155 17 25 0126631+354579 37 S
79395 20 711A   0796 E 20200729222743161 17 25 0131587+342093 37 S
79395 20 711A   0796 E 20200729222754157 17 25 0137562+323613 37 S

As Leo reported, the above are close to the prediction given by the following search TLE that fits
Russell's observations of July 26:

1 79395U 79395A   20208.97960996  .00000000  00000-0  00000-0 0    06
2 79395  54.0811 237.7091 0000001   0.0000  73.5075 14.88740000    03

The following table compares the key elements of the search TLE and those derived by fitting a
circular orbit to the first and last of Leo's three points:

             Search    Leo's Obs
 Inc, deg     54.08      54.02
RAAN, deg    224.7      225.1
  n0, rev/d   14.8788   14.8874

It seems highly likely that Leo and Russell observed the same object. If it was the NROL-129
Minotaur 4th stage, then the predicted magnitude at the time of Leo's observations was
6.7 +/-1.2, with 95% confidence.

Here is an updated search TLE, fit to Leo's and Russell's observations:

NROL-129 search                                          601 X 603 km
1 79395U 79395A   20211.91999032  .00000000  00000-0  00000-0 0    07
2 79395  54.0715 225.0568 0001000 359.9586   0.1408 14.88740043    03
Arc 20200726.98-0729.94 WRMS resid 0.012 totl 0.004 xtrk

I am being a bit conservative by not assigning an ID from the NROL-129 launch just yet. However, I
suggest that any new observations of an object in the above orbit be reported as 2020-046E / 45877
(the Minotaur 4th stage). We would re-consider that ID depending on what we learn about the
payloads, should they be found.

Ted Molczan

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Received on Thu Jul 30 2020 - 11:24:58 UTC

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