USA 125 r2 aka 96038C - identification

Ted Molczan (
Fri, 17 Dec 1999 11:46:39 -0500

This is a follow-up to David Brierley's earlier post of his observations of
this object, and Pierre Neirinck's first elements:

USA 125 r2       2.0  0.0  0.0  6.2 v
1 23947U 96038  C 99350.31952770  .00003200  00000-0  14718-2 0    13
2 23947  55.3273 330.1598 5035331  55.8656 342.1975  5.47041462    00

This object appears to be the perigee kick motor of USA 125 (96038A / 23945),
which was launched in early July 1996, and tracked by several SeeSat-L

96038A had visual characteristics similar to 89061B and 92086B, both of which
went to Molniya orbits, so that became the expectation for 96038A. The first
manoeuvre should have resulted in a 2 m diameter rocket motor in an
intermediate highly elliptical orbit.

96038A was last reported seen at day 96190.9465 by Pierre Neirinck, and first
reported missing at day 96191.2597 by an observer who prefers anonymity, which
indicated that the expected major maneouvre had taken place.

This is Pierre's final 96038A elset:

1 23945U 96038  A 96191.18012210  .00044450  00000-0  15298-3 0    97
2 23945  54.9692 157.6756 0006456 325.6910  34.4399 15.88888486    00

Precessing the suspected 96038C back to the mid-point of the period during
which the maneouvre likely took place, day 96191.1, 96038C and 96038A would
have been within 8.7 deg of each other in RAAN; and 96038C would have had an
argument of perigee of about 287 deg - about as expected for a Molniya orbit.

In computing the precession, I accounted for decay, using mean values of ndot/2
no greater than 0.00001 rev/d^2, since much of the past 3.5 years were near
solar minimum.

96038C's standard magnitude of 6.2 (1000 km, 50 percent illuminated) is close
to that of 89061D and 92086C, and consistent with a 2 m diameter object.

The orbit and visual appearance strongly suggest that David is tracking 96038C.

Ted Molczan

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