Re: NROL-47 search elements from radio observations

NROL-47 continues to transmit on S-band, and Doppler curves have been
obtained for all but two out of twenty-two orbits so far. The
additional observations show that a much better orbit can be
determined by using data from all but the first three orbits. This may
indicate that NROL-47 performed a manouvre early on in the mission.

Fitting the Doppler curves from my station yields this estimate:

NROL-47 Radio data from station 4171                      1052x1053km
1 70003U          18013.76201550  .00000000  00000-0  00000-0 0    02
2 70003 106.0107 137.6434 0000643 338.6702 292.8564 13.55435329    03
# 20180113.51-20180114.55, 4133 measurements, 0.120 kHz rms

This is very similar to that using only data from Scott's station:

NROL-47 Radio data from station 8049                      1049x1056km
1 70004U          18013.76201550  .00000000  00000-0  00000-0 0    03
2 70004 105.9701 137.4364 0004503 327.7129 303.7443 13.55520691    08
# 20180113.21-20180114.38, 2309 measurements, 0.254 kHz rms

These orbital estimates show that the orbit is nearly circular, and
the inclination is almost 106 degrees. The orbital altitude is
somewhat below the operational FIA Radar altitude of 1100 to 1110 km,
but this was also the case for the earlier FIA Radar satellites in the
first few days after launch. It is likely that NROL-47 will, in the
near future, move to the operational FIA Radar orbit.

The orbital estimates below are for circular orbits over a range of
inclinations, to guard against possible problems with the orbits
fitted to the data. Please use these as a guide when searching, but
focus on the 106 degree inclined orbit.

Happy hunting!
   Cees and Scott

1 70003U          18013.76201550  .00000000  00000-0  00000-0 0    02
2 70003 104.0000 138.3721 0010000   0.0000 271.6770 13.55500463    05
# 20180113.51-20180114.55, 4133 measurements, 1.398 kHz rms
1 70003U          18013.76201550  .00000000  00000-0  00000-0 0    02
2 70003 105.0000 137.9517 0010000   0.0000 271.5883 13.55474667    04
# 20180113.51-20180114.55, 4133 measurements, 0.727 kHz rms
1 70003U          18013.76201550  .00000000  00000-0  00000-0 0    02
2 70003 106.0000 137.6224 0010000   0.0000 271.4205 13.55440760    01
# 20180113.51-20180114.55, 4133 measurements, 0.133 kHz rms
1 70003U          18013.76201550  .00000000  00000-0  00000-0 0    02
2 70003 107.0000 137.3488 0010000   0.0000 271.2725 13.55394935    08
# 20180113.51-20180114.55, 4133 measurements, 0.711 kHz rms
1 70003U          18013.76201550  .00000000  00000-0  00000-0 0    02
2 70003 108.0000 137.1050 0010000   0.0000 271.2453 13.55336180    08
# 20180113.51-20180114.55, 4133 measurements, 1.427 kHz rms
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