Electronic Telegram No. 2919
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET P/2011 W1 (PANSTARRS)
     Richard Wainscoat and Larry Denneau report the discovery of a comet on
images taken with the Pan-STARRS 1 telescope on Haleakala by N. Primak, A.
Schultz, S. Watters, J. Thiel, and T. Goggia (discovery observations
tabulated below); the object has a distinctly soft point-spread function
compared to stars in the same field.  Follow-up observations by Wainscoat and
Marco Micheli using the 3.6-m Canada-France-Hawaii Telescope on Nov. 27 UT
(queue observer Adam Draginda) in relatively poor seeing conditions (stellar
FWHM = 1".3), the object was clearly seen to be extended, with a FWHM = 2".4;
the coma appears to be slightly asymmetric, with a diffuse extension to the
west.  Following posting on the Minor Planet Center's NEOCP webpage, other
CCD astrometrists have also found the object to show cometary appearance.
L. Buzzi (Varese, Italy; 0.60-m f/4.6 reflector) found a round 9" coma of
red mag 18.5 on stacked images taken on Nov. 26.9.  H. Sato (Tokyo, Japan;
remotely using a 0.51-m f/4.5 reflector at the RAS Observatory near Mayhill,
NM, U.S.A.) found a moderately condensed coma of diameter 16" with a total
V-band magnitude of 18.4 within a circular 8".2-aperture radius on Nov. 27.2.
P. Birtwhistle (Great Shefford, Berkshire, England; 0.40-m f/6 reflector)
finds a circular coma with a diameter up to 8" and red mag 18.2 but no trace
of tail on images from Nov. 28.0.

     2011 UT             R.A. (2000) Decl.       Mag.
     Nov. 26.54431    5 09 49.12   +17 41 03.7   20.1
          26.55916    5 09 48.54   +17 41 02.6   20.1
          26.57402    5 09 47.99   +17 41 01.0   19.5
          26.58829    5 09 47.40   +17 41 00.1   19.4

The available astrometry (including prediscovery Spacewatch observations from
Nov. 23), the following preliminary elliptical orbital elements by G. V.
Williams, and an ephemeris appear on MPEC 2011-W66.

     T = 2012 June  1.161 TT          Peri. = 307.978
     e = 0.29800                      Node  = 160.578   2000.0
     q = 3.26921 AU                   Incl. =   3.760
       a =  4.65702 AU     n = 0.098071     P =  10.0 years


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2011 CBAT
2011 November 28                 (CBET 2919)              Daniel W. E. Green