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IAUC 8449: C/2004 X1; 2004gc; V2540 Oph

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IAUC number

                                                  Circular No. 8449
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)

     A. Milner, Lincoln Laboratory, reports the discovery by LINEAR
of a comet with an apparent tail in p.a. 90 deg (discovery
observation below).  Following posting on the 'NEO Confirmation
Page', other observers have confirmed the object's cometary nature
from CCD images, including E. J. Christensen at Catalina (0.68-m
Schmidt telescope, Dec. 9.10-9.11 UT; coma diameter about 8" with
red mag 16.2-16.6 and faint 20" tail in p.a. 60 deg) and M. Tichy,
M. Kocer, and J. Ticha at Klet (1.06-m KLENOT telescope, Dec. 9.70;
diffuse with coma diameter 25" and a wide tail in p.a. 70 deg).

     2004 UT             R.A. (2000) Decl.       Mag.
     Dec.  7.07585   21 56 11.20   - 4 32 40.1   18.7

The available astrometry, preliminary parabolic orbital elements (T
= 2004 Nov. 7.37 TT, q = 0.8103 AU, Peri. = 355.10 deg, Node = 0.18
deg, i = 5.67 deg, equinox 2000.0), and an ephemeris appear on MPEC
2004-X31.  It is possible that this comet is of short period.

     M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics; and T. Matheson, National Optical
Astrononmy Observatory, report that a spectrogram (range 350-740
nm) of SN 2004gc (cf. IAUC 8442), obtained by M. Calkins on Dec.
8.42 UT with the F. L. Whipple Observatory 1.5-m telescope (+
FAST), shows it to be a supernova of type Ia, with a spectral-
feature age (Riess et al. 1997, A.J. 114, 722) of about 3 weeks
past maximum brightness.  Adopting the NED recession velocity of
9620 km/s for the host galaxy, the supernova expansion velocity,
derived from the minimum of Si II (rest 635.5 nm), is about 9400

     T. Ak, Istanbul University; A. Retter, Pennsylvania State
University; and A. Liu, Exmouth, W. Australia, report that
unfiltered CCD photometric observations were made of V2540 Oph
using a 0.3-m telescope at Exmouth over 26 nights between May 2003
and June 2004.  The analysis suggests a periodic signal with an
amplitude of about 0.02 mag.  The ephemeris is T_min = HJD
2453151.3098 (+/- 0.0062) + 0.284750 (+/- 0.000008)E.  The
periodicity very likely represents the binary period.

                      (C) Copyright 2004 CBAT
2004 December 9                (8449)            Daniel W. E. Green

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