[IAUC] CBET 2852: 20111003 : COMET C/2011 S2

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                                                  Electronic Telegram No. 2852
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2011 S2
     R. A. Kowalski reports the discovery of a comet on CCD images obtained
with the Catalina Sky Survey's 0.68-m Schmidt reflector (discovery
observations tabulated below), the object described as having a bright,
condensed coma 15" in diameter with a broad tail at least 1' long in p.a. 300
deg.  Follow-up observations by A. R. Gibbs with the Mt. Lemmon 1.5-m reflector
on Oct. 1.51 UT show a 55" tail in p.a. 300 deg.  After posting on the Minor
Planet Center's NEOCP webpage, other CCD astrometrists have commented on the
object's cometary appearance.  E. Pettarin (Farra d'Isonzo, Italy, 0.40-m
f/4.5 reflector; Oct. 1.1) measures a 60" tail in p.a. 300 deg.  A. Knoefel
(Drebach, Germany, 0.5-m f/5 reflector; Oct. 1.1) finds a 2' tail.  L. Buzzi
(Varese, Italy, 0.60-m f/4.6 reflector; Oct. 1.1) reports a condensed coma
12" in size with a tail at least 60" long in p.a. around 296 deg.  P.
Birtwhistle (Great Shefford, Berkshire, England, 0.40-m f/6 Schmidt-Cassegrain
reflector; Oct. 1.2) notes a concentrated coma of diameter 10" and total mag
16.4, with a fan tail spanning p.a. 238-326 deg, having a brighter central
spine 1'40" long in p.a. 300 deg.  Images taken by R. Holmes (Ashmore, IL,
USA, 0.61-m f/4 astrograph; Oct. 1.4) and measured by T. Vorobjov, L. Buzzi,
and S. Foglia reveal a 10" x 15" coma elongated in p.a. 290 deg with a tail
1'-2' long in the same position angle.  E. Guido, G. Sostero, and N. Howes
(0.25-m f/3.4 reflector remotely at the GRAS Observatory near Mayhill, NM,
U.S.A.; Oct. 1.4) report a condensed coma about 10" in diameter that is
elongated toward p.a. 295 deg.  H. Sato (Tokyo, Japan; remotely using a 0.51-m
f/4.5 reflector at the GRAS Observatory near Mayhill; Oct. 1.5) finds a coma
of diameter 25" with a tail; the total red mag was 16.0 in a circular aperture
of radius 13".  S. Baroni, L. Buzzi, P. Concari, S. Foglia, G. Galli, and M.
Tombelli write that four stacked 180-s images obtained with a 0.18-m f/2.8
Newtonian reflector on Oct. 1.5 show a round coma of diameter 12".  R-band
images taken by W. H. Ryan and E. V. Ryan (Magdalena Ridge Observatory, 2.4-m
f/8.9 reflector) reveal a prominent tail at p.a. about 335 deg on Oct. 1.5 and
p.a. about 300 deg on Oct. 2.5.  G. Hug (Scranton, KS, U.S.A., 0.56-m
reflector; Oct. 2.5) reports a narrow, fan-shaped tail extending 2'.5 in p.a.
about 300 deg.

     2011 UT             R.A. (2000) Decl.       Mag.   Observer
     Sept.30.48411    9 12 10.05   +20 18 30.3   15.7   Kowalski
          30.48640    9 12 10.68   +20 18 24.6   15.7     "
          30.48868    9 12 11.12   +20 18 20.3   15.7     "
          30.49094    9 12 11.83   +20 18 15.9   15.7     "

The available astrometry, the following preliminary parabolic orbital elements
by G. V. Williams, and an ephemeris appear on MPEC 2011-T12.  The orbit of
this object is essentially indeterminate at the present time.  It is possible
that this is a short-period comet.  Among the wide range of possible short-
period orbits are orbits that appear similar to that of P/2006 T1 (Levy).
Initial attempts to link the two apparitions have not been successful.
Further observations are encouraged.

     T = 2011 Oct. 23.524 TT          Peri. = 188.828
                                      Node  = 288.573   2000.0
     q = 1.13259 AU                   Incl. =  17.319


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2011 CBAT
2011 October 3                   (CBET 2852)              Daniel W. E. Green