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IAUC 7966: C/2002 Q2

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                                                  Circular No. 7966
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     S. S. Sheppard and D. C. Jewitt, University of Hawaii, report
that CCD images of C/2002 Q3 on Sept. 4.3 and 5.3 UT taken with the
2.2-m reflector at Mauna Kea show three separate fragments a few
arcsec apart; the brightest, component A (R = 21.7; photometry
through a 1"-radius aperture), appears elongated; component B was
at R = 22.1 and component C at 22.6.  The astrometric positions are
given on MPEC 2002-R20.
     Z. Sekanina, Jet Propulsion Laboratory, communicates:
"Applying my model for the split comets and using a code developed
recently by P. W. Chodas and myself, I determined from 46
differential astrometric observations of the C/2002 Q2-C/2002 Q3
pair, taken between Aug. 26 and Sept. 1 (MPECs 2002-Q37, 2002-Q50,
2002-Q51, 2002-R19, and 2002-R20), that C/2002 Q2 is the main comet,
with companion C/2002 Q3 having broken off from it in 1969.2 +/-
5.1 yr at a distance of some 57 +/- 6 AU from the sun and > 30 AU
south of the ecliptic.  The separation velocity was only 0.15 +/-
0.04 m/s, and the secondary comet has been subjected to a relative
deceleration of 33.2 +/- 5.1 units of 10**-5 solar gravitational
acceleration.  The mean residual from the solution is +/- 1".03.
The time of separation may be even more uncertain than indicated,
if the orbits depart significantly from parabolas.  Because of
too-limited information on the C/2002 Q3 system (see above)
available at this time, the fragmentation sequence for its three
components remains unclear, with two extreme scenarios possible:
either they all separated from C/2002 Q2 a long time ago (say,
before about 1985) or two of them were released very recently
(during the past several months) from the third.  If so, component
C is the parent to component B and perhaps to component A as well,
although A could have alternatively separated from B after B broke
off from C.  Continuing observations of these components should
soon constrain the range of possible scenarios.  If the relative
configuration of A, B, and C remains essentially unchanged over a
period of a few weeks, they all are old fragments.  If their
separations begin to increase rapidly (by a factor of about 2 or
more in a couple of weeks) and the line joining them rotates toward
the north-south direction, they are products of recent events.  The
predicted separation distances and position angles (for 0h TT) of
C/2002 C3 from C/2002 C2 are:  Sept. 3, 3137", 304.5 deg; 8, 3630",
314.0 deg; 13, 4110", 321.3 deg; 18, 4423", 326.5 deg; 23, 4452",
330.0 deg; 28, 4207", 332.2 deg; Oct. 3, 3800", 333.7 deg."

                      (C) Copyright 2002 CBAT
2002 September 6               (7966)            Daniel W. E. Green

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