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IAUC 9243: P/2011 W1

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                                                  Circular No. 9243
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
New postal address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBATIAU@EPS.HARVARD.EDU           ISSN 0081-0304
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET P/2011 W1 (PANSTARRS)
     As first reported on CBET 2919, 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.  In 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 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 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 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 initial astrometry (including prediscovery Spacewatch
observations from Nov. 23) appeared on MPEC 2011-W66.  The
following revised orbital elements appeared on MPEC 2011-Y02:

     T = 2012 Jan. 24.5590 TT         Peri. = 282.8896
     e = 0.289743                     Node  = 161.8563  2000.0
     q = 3.308795 AU                  Incl. =   3.7175
       a =  4.658586 AU    n = 0.0980218    P =  10.06 years

                      (C) Copyright 2011 CBAT
2011 December 17               (9243)            Daniel W. E. Green

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