Electronic Telegram No. 261
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html


COMET C/2005 T4 (SWAN)
     R. D. Matson, Newport Coast, California; and M. Mattiazzo, Wallaroo,
South Australia, have independently reported the presence of a comet in
SOHO SWAN data during the first half of October.  Matson indicates that the
comet was fainter than mag 10, while Mattiazzo suggests fading from mag
about 9 on Oct. 9 to mag 10 on Oct. 13.  E. J. Christensen reports that
Catalina Sky Survey (0.68-m Schmidt) images on Oct. 22.1 UT show a moderately
condensed, roughly circular coma of diameter about 2 arcmin in three coadded
20-second exposures.  R. H. McNaught, observing with the 1.0-m f/8 reflector
at Siding Spring Observatory on Oct. 22.4, reports a diffuse 1-arcmin coma
with 3-arcsec (FWHM) central condensation (used for magnitude estimate).

     2005 UT             R.A. (2000) Decl.       Mag.   Observer
     Oct.  6         15 00.7       - 0 20               Matson
           9         15 29.2       - 3 28                 "
          11         15 47.9       - 5 10                 "
          13         16 06.9       - 6 43                 "
     Oct. 22.06892   16 27 47.50   - 9 13 25.2   12.4   Christensen
          22.07064   16 27 47.68   - 9 13 27.0            "
          22.07230   16 27 47.91   - 9 13 28.7            "
          22.39354   16 28 24.32   - 9 17 53.4   18.1   McNaught
          22.39504   16 28 24.50   - 9 17 55.1   18.0     "
          22.39654   16 28 24.67   - 9 17 56.3   18.0     "
          22.39809   16 28 24.83   - 9 17 57.4   17.9     "
          22.39960   16 28 24.99   - 9 17 58.8   17.9     "
          22.40110   16 28 25.18   - 9 18 00.0   17.7     "

     Very preliminary parabolic orbital elements by the undersigned:

     T = 2005 Oct.  2.951 TT          Peri. =  34.036
                                      Node  =  28.784   2000.0
     q = 0.62259 AU                   Incl. = 160.402

2005 TT     R. A. (2000) Decl.     Delta      r    Elong. Phase      m1
Oct. 17    16 15.16    - 7 46.5    0.958    0.693   41.5   72.3     13.3
     22    16 27.66    - 9 12.3    1.153    0.745   39.7   58.7     14.0
     27    16 35.52    -10 14.8    1.338    0.806   36.8   47.7     14.7
Nov.  1    16 40.94    -11 03.1    1.511    0.873   33.3   38.7     15.3
      6    16 45.03    -11 42.3    1.671    0.944   29.5   31.1     15.9


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

                         (C) Copyright 2005 CBAT
2005 October 22                  (CBET 261)               Brian G. Marsden