Re: NROL-82 search elements

From: C. Bassa via Seesat-l <seesat-l_at_satobs.org>
Date: Tue, 27 Apr 2021 13:15:02 +0200
The following orbital elements are based on the observations obtained
over the 2nd and 3rd orbit of NROL-82.

NROL-82                                                  522 x 761 km
1 99596U          21117.05771367  .00000000  00000-0  50000-4 0    08
2 99596  98.0546 230.2670 0169852  86.6649 330.9798 14.76209142    07
# 20210426.99-20210427.06, 18 measurements, 0.008 deg rms

The orbit is less eccentric compared to typical KH-11 missions, which
usually have 260 x 1000 km orbits. However, the mean motion is close
to that of those missions. For example, both USA 224 [37348/11002A]
and USA 245 [39232/13043A] have a mean motion near 14.81 revolutions
per day.

Interestingly, the orbital plane of the NROL-82 payload is almost
co-planar with that of USA 224, and furthermore, both satellites are
in the same orbital phase. Both objects passed the ascending node at
10:53:40UTC today only 7 seconds apart! Over the course of the first
two days after launch, the distance between USA 224 and NROL-82 varies
from 3000km to 100 km!

Though there are still some uncertainties about the precise parameters
of the NROL-82 orbit, it certainly appears that USA 224 is, and has
been, in a position to monitor NROL-82 during the early checkout phase
after launch.

Regards,
    Cees
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Received on Tue Apr 27 2021 - 06:15:47 UTC

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