Electronic Telegram No. 4235
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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Prepared using the Tamkin Foundation Computer Network


COMET P/2010 V1 = P/2015 Y2 (IKEYA-MURAKAMI)
     Z. Sekanina, Jet Propulsion Laboratory, writes that tentative analysis
of the offsets of nuclei A and B from January 1-4 suggests that they separated
from the parent comet in the course of the 2010 return and quite possibly
during the major outburst, which is estimated to have begun on 2010 Nov. 1,
some 20 days after perihelion and shortly before the comet was discovered
(IAUCs 9175, 9176).  The leading nucleus B is with near certainty the primary,
more massive fragment, while nucleus A is its companion; this is plainly
reflected in their times of perihelion passage, with nucleus B preceding by
0.017 day (MPECs 2016-A10, 2016-A36).  The slightly greater brightness of A is
apparently due to its current activity.  Independent evidence comes from the
different tail orientations, reported by M. Micheli et al. (CBETs 4230, 4231).
The tail of component B, in p.a. 290 deg, is directed along the projected
orbit behind it (and towards component A) and is in fact a trail of coarse
debris originating at the time of splitting.  On the other hand, the tail of
nucleus A, in p.a. about 240 deg, is closer to the anti-solar direction and
contains recent ejecta.  Once nucleus B grows more active, it should become
as bright as A or even brighter.  The analysis suggests a very low
differential nongravitational acceleration between both fragments and their
separation with a submeter-per-second velocity.  Both may survive the 2016
March perihelion and beyond.
     Predicted separations and position angles of nucleus A relative to B
(0h UT):  Jan. 13, 112", 294 deg; Jan. 23, 121", 293 deg; Feb. 2, 126", 291
deg; Feb. 12, 126", 289 deg; Feb. 22, 123", 288 deg.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2016 CBAT
2016 January 10                  (CBET 4235)              Daniel W. E. Green