Electronic Telegram No. 3112
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 C/2012 K1 (PANSTARRS)
     Larry Denneau and Richard Wainscoat, Institute for Astronomy, University
of Hawaii, report the discovery of a comet in two r-band 40-s exposures taken
with the 1.8-m Pan-STARRS 1 telescope at Haleakala (discovery observations
tabulated below), with the object having a distinctly soft point-spread
function, with full-width-at-half-maximum of approximately 1".9, while
nearby stars have FWHM of 0".9; the object shows a hint of a low-surface-
brightness extension towards position angle 160 degrees.  Wainscoat and
Denneau later examined four images of the object taken with the Pan-STARRS1
telescope on May 17.55-17.58 UT (two 43-s exposures taken through the g
filter, and two 40-s exposures taken through the r filter); although the
seeing in these four images was relatively poor, the object is seen to be
clearly extended.  After posting on the Minor Planet Center's NEOCP webpage,
other CCD astrometrists have commented on the object's cometary appearance.
H. Sato (Tokyo, Japan; V-band images taken remotely with a 0.43-m f/6.8
astrograph + f/4.5 focal reducer at the RAS Observatory near Mayhill, NM,
U.S.A. on May 20.3) reports a round coma of diameter 10" with total magnitude
19.0 as measured within a circular aperture of radius 5".7.  Twenty-six
stacked 60-s images taken by R. Holmes (Ashmore, IL, USA; 0.61-m f/4
astrograph; measured by T. Vorobjov, L. Buzzi, and S. Foglia) show the
object to be very condensed but with a FWHM profile that is notably larger
than those of nearby stars (4".8 vs. 4".0).

     2012 UT             R.A. (2000) Decl.       Mag.
     May  19.45254   17 36 52.58   +13 27 48.6   19.7
          19.46221   17 36 52.27   +13 27 50.3   19.7
          19.54596   17 36 49.67   +13 28 04.6   19.3
          19.55550   17 36 49.37   +13 28 06.2   19.3

     The available astrometry (May 17-20), the following preliminary parabolic
orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2012-K36.

     T = 2015 Apr. 10.0788 TT         Peri. = 177.5939
                                      Node  = 316.8779  2000.0
     q = 2.741992 AU                  Incl. = 141.8428


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2012 CBAT
2012 May 21                      (CBET 3112)              Daniel W. E. Green