Electronic Telegram No. 3688
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/2013 US_10 (CATALINA)
     An apparently asteroidal object discovered in Catalina Sky Survey images
taken by R. A. Kowalski on Oct. 31 UT (discovery observations tabulated
below), and given the minor-planet designation 2013 US_10 on Nov. 2 by the
Minor Planet Center on MPEC 2013-V05, has been found to show cometary
appearance by Richard Wainscoat on prediscovery images obtained with the
Pan-STARRS1 telescope at Haleakala following a request by G. V. Williams.  In
each of the four 45-s w-band images taken on Aug. 14, the point-spread function
(PSF) of the object has a higher FWHM than adjacent stars, though there is no
obvious appearance of a tail or extended coma.  Marco Micheii and Wainscoat
then scheduled queue observations with the Canada-France-Hawaii Telescope
(CFHT) on Nov. 5 (queue observer Lisa Wells); sixteen 60-s r-band exposures
showed the PSF of 2013 US_10 to be extended relative to adjacent stars; eight
co-added images with the best seeing conditions reveal no evidence of a tail,
but 2013 US_10 appears to be slightly asymmetric and is slightly more extended
towards p.a. approximately 50 degrees.  Five additional 60-s r-band CFHT
exposures were obtained by Wainscoat and Micheli on Nov. 6 (queue observer
David Woodworth), tracked at the rate of 2013 US_10, and the object appears
extended relative to adjacent stars in each image; the shape of 2013 US_10 in
each image is clearly asymmetric, and is extended slightly towards p.a.
approximately 45 degrees.

     2013 UT             R.A. (2000) Decl.       Mag.   Observer
     Oct. 31.16159   23 23 22.78   -14 15 07.6   18.6   Kowalski
          31.17176   23 23 22.48   -14 15 09.7   18.8     "
          31.18194   23 23 22.22   -14 15 11.3   18.5     "
          31.23046   23 23 21.05   -14 15 16.5   18.6     "
          31.23649   23 23 20.84   -14 15 17.6   18.4     "
          31.24254   23 23 20.70   -14 15 19.4   18.6     "
          31.24855   23 23 20.49   -14 15 20.4   18.1     "

The available astrometry (including prediscovery observations also from
Catalina on Sept. 1, 12, and 23, and by L. Elenin at Mayhill on Sept. 9 -- all
of the prediscovery astrometry being identified by T. Spahr after the issuance
of MPEC 2013-V05; note that the Sept. 12 Catalina observations published on
MPEC 2013-V05 refer to a different object), the following parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2013-V31.

                    Epoch = 2015 Dec.  4.0 TT
     T = 2015 Nov. 16.0225 TT         Peri. = 340.3273
     e = 1.000369                     Node  = 186.1603  2000.0
     q = 0.824945 AU                  Incl. = 148.9055


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

                         (C) Copyright 2013 CBAT
2013 November 6                  (CBET 3688)              Daniel W. E. Green