Central Bureau for Astronomical Telegrams
IAUC 6301: 73P
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Circular No. 6301
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
COMET 73P/SCHWASSMANN-WACHMANN 3
MPC 26211 contains observations of discrete components A, B, C and
possibly D by J. V. Scotti (Spacewatch) and A. Galad (Modra) during 1995
Dec. 27-29. Designated from west to east and with C the brightest, the
components A, B and C can be associated with the three principal brightness
peaks described by H. Bohnhardt and H. U. Kaufl at the European Southern
Observatory on Dec. 12 (IAUC 6274). Numerous further observations at
seven additional observatories during 1995 Dec. 23-1996 Jan. 21 (notably
a series by J. Chen and D. Jewitt with the University of Hawaii's 2.2-m
reflector during Dec. 23-27) are published on MPC 26444-26445. Bohnhardt
and Haufl report that further observations with the New Technology
Telescope show B separated from C by 4".6 (in p.a. 253 deg) on Jan. 7.0 UT
and by 6".11 (in p.a. 244.8 deg) on Jan. 31.0; the corresponding separations
of A from C were 10".1 (in p.a. 247 deg) and 17".05 (in p.a. 240.5 deg).
Furthermore, their deconvolution of images obtained by K. Reinsch and
J. Storm with ESO 2.2-m and 1.5-m reflectors shows A at 1".4 (in p.a.
280 deg) and 1".8 (in p.a. 270 deg) from C on Nov. 28 and Dec. 2,
respectively.
Z. Sekanina, Jet Propulsion Laboratory, communicates: "Solutions
derived from the extensively tested model for split comets (Sekanina
1982, in Comets, University of Arizona Press, p. 251), applied to up to
13 of the most consistent observations obtained with large-aperture
telescopes, indicate that the component B broke off from the primary
component C most probably about 1995 Oct. 24 with a separation velocity of
about 1.3 m/s and with a relative nongravitational deceleration of 4.4
(in units of 10**-5 of the solar attraction). This event was evidently
followed by a secondary splitting of component B, which gave birth to
component A on or about Dec. 1 (as independently suggested by Bohnhardt
and Haefl), with a separation velocity possibly as high as 4.6 m/s and
a deceleration of, very crudely, 40 units. This B-A scenario offers a
better fit to the observations than the alternative of having A separate
from C in early November. There now appears to be no escape from the
conclusion that the brightness outburst, which apparently occurred
between Sept. 5 and 8 (IAUC 6227), preceded the first breakup episode
by at least six weeks. As for component D, it seems that this might have
separated from C in late November with an acceleration of more than 50
units. At least two further possible short-lived, high-acceleration
condensations have been mentioned by other observers."
(C) Copyright 1996 CBAT
1996 February 1 (6301) Brian G. Marsden
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