Hitomi: evidence of more than one debris-shedding

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Sat, 2 Apr 2016 13:49:44 -0400
Conjunction analyses between Hitomi (16012A / 41337) and the first two TLEs of 16012K / 41441, reveal that the two
objects separated on 2016 Mar 26 around 02:35 UTC to 02:45 UTC. That was about one hour later than JSpOC's initial
estimate of the time of the debris-shedding: 01:42 UTC +/- 11 min. Several of the other fragments appear to have
separated from Hitomi in the vicinity of 01:42 UTC; therefore, the later time of 16012K's separation is evidence of more
than one debris-shedding event.

16012K separated when Hitomi happenned to be close to the perigee of its 568 X 584 orbit. 16012K is in a 533 X 570
orbit, differing from Hitomi in argument of perigee by very roughly 180 deg, with minimal planar differences; therefore,
it was ejected in approximately opposite the direction of Hitomi's motion, at a relative velocity of roughly 14 m/s.

Assuming Hitomi was tumbling, then it seems possible for 16012K to have been flung off of it due to the rotation. Based
on Brad Young's observation on Apr 02 UTC that Hitomi was flashing with a period of 2.589 s, I estimated that its period
of rotation was about 5.2 s. With that period, an object about 11.6 m from the axis of rotation would have a speed of 14

Ted Molczan

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Received on Sat Apr 02 2016 - 12:50:29 UTC

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