[IAUC] IAUC 9236: P/2011 U1; P/2011 U2 [25139-2012/04-R1]

[quai en eps.harvard.edu]

                                                  Circular No. 9236
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 en EPS.HARVARD.EDU           ISSN 0081-0304
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Prepared using the Tamkin Foundation Computer Network


COMET P/2011 U1 (PANSTARRS)
     Larry Denneau, Richard Wainscoat, and Henry Hsieh, Institute
for Astronomy, University of Hawaii, report the discovery of a
comet on CCD images taken with the "Pan-STARRS 1" 1.8-m telescope
at Haleakala (discovery observations tabulated below); stacked
discovery frames show FWHM for the comet of 1".5, compared with
1".1 for nearby stars.  Confirming images taken with the Canada-
France-Hawaii Telescope by M. Micheli (measured by Hsieh) show a
diffuse, low-level coma with a slight extension (about 3"-4" long)
to the west.  After posting on the Minor Planet Center's NEOCP
webpage, Shinsuke Abe reported a tenuous tail-like structure
around p.a. 270 deg on Oct. 26.4 UT (0.81-m telescope; details on
CBET 2874).

     2011 UT             R.A. (2000) Decl.       Mag.
     Oct. 23.45242    5 06 41.93   + 2 46 50.5   21.0
          23.49712    5 06 41.72   + 2 46 38.1   21.3

The initial astrometry was published on MPEC 2011-U84.  Elliptical
orbital elements by G. V. Williams (cf. MPEC 2011-V31; epoch 2012
June 2.0 TT):

                    Epoch = 2012 June  2.0 TT
     T = 2012 June 19.4602 TT         Peri. = 352.3249
     e = 0.412752                     Node  = 135.1318  2000.0
     q = 2.368574 AU                  Incl. =  15.2299
       a =  4.033344 AU    n = 0.1216764    P =   8.10 years


COMET P/2011 U2 (BRESSI)
     Terrence H. Bressi reports the discovery of a diffuse comet on
CCD mosaic images taken with the Spacewatch 0.9-m f/3 reflector at
Kitt Peak (discovery astrometry tabulated below); a short tail
extends 7" from the central condensation in p.a. 260 deg.  After
posting on the Minor Planet Center's NEOCP webpage, other
astrometrists also noted the cometary appearance; additional
details appear on CBET 2875.

     2011 UT             R.A. (2000) Decl.       Mag.   Observer
     Oct. 24.20595    2 59 13.56   +25 10 56.7   19.4   Bressi
          24.24155    2 59 12.44   +25 10 51.9   19.4     "

The initial astrometry appeared on MPEC 2011-U85.  Revised
elliptical orbital elements by G. V. Williams, from 55 observations,
2011 Oct. 24-Nov. 4 (mean residual 0".4; cf. MPEC 2011-V31):  Epoch
= 2012 Sept. 30.0 TT, T = 2012 Oct. 7.3238 TT, q = 4.804725 AU, e =
0.104716, Peri. = 173.2533 deg, Node = 266.1304 deg, i = 9.8163 deg
(equinox 2000.0), P = 12.43 years.


                      (C) Copyright 2011 CBAT
2011 November 9                (9236)            Daniel W. E. Green