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IAUC 8434: C/2003 S4; 2004fx

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IAUC number

                                                  Circular No. 8434
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)

    Z. Sekanina, Jet Propulsion Laboratory, writes: "Application of
my comet fragmentation model (Sekanina 1982, in Comets, Univ. of
Arizona Press, p. 251) to this comet's observed duplicity (MPECs
2004-T44 and 2004-U10) shows that component B is the principal
nucleus.  This result is supported by the location of component A
between components B and C, a suspected third fragment, on an image
taken by R. Ferrando on 2004 Oct. 9 (see
http://www.aerith.net/comet/catalog/2003S4/pictures.html).  The
astrometric observations made in Sept.-Oct. 2004 allow one to
determine four of the model's five parameters for component A.  The
radial component of its separation velocity from B is indeterminate.
Solutions with this velocity component assumed to point away from
the sun provide marginally better data matches.  When it is limited
to a range from 0 to 2 m/s, the time of splitting comes out to be
between 2004 May 23 and June 17 (3 days before to 22 days after
perihelion) at 3.86 AU from the sun, with the differential
nongravitational deceleration decreasing from 140 to 90 units of
10**-5 solar attraction and with the transverse and normal
components of the separation velocity near 0.8 m/s in the direction
opposite the orbital motion and 0.2 m/s pointing below the orbital
plane, respectively.  The high deceleration of the companion
(nucleus A) indicates that it is a short-lived fragment with an
estimated lifetime of 12-33 equivalent days.  At a heliocentric
distance of about 4 AU this means that the secondary can possibly
be observed for several more months, unless the comet's rapid
fading, apparently triggered by this nucleus fragmentation,
continues.  Predicted separations and position angles of A relative
to B are as follows (0 TT, equinox 2000.0): 2004 Nov. 11, 12".9,
289 deg; Dec. 1, 13".9, 296 deg; Dec. 21, 14".7, 301 deg; 2005 Jan.
10, 15".5, 304 deg; Jan. 30, 16".5, 305 deg; Feb. 19, 17".8, 304
deg; Mar. 11, 19".6, 301 deg."

SUPERNOVA 2004fx IN MCG -02-14-3
     M. Salvo, B. Schmidt and M. Bessell, the Australian National
University (ANU), report that a spectrogram (range 350-530 nm) of
SN 2004fx (cf. IAUC 8431), obtained with the ANU 2.3-m telescope (+
Double-Beam Spectrograph) at Siding Spring on Nov. 8.54 UT, shows
the P-Cyg lines of H_beta, H_gamma, and H_delta typical of a type-
II supernova approximately 2 weeks after explosion.  The expansion
velocity derived from the Fe II 5169 line, also visible in the
spectrum, is 6600 km/s, after correcting for the NED recession
velocity of the host galaxy.

                      (C) Copyright 2004 CBAT
2004 November 10               (8434)            Daniel W. E. Green

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