Electronic Telegram No. 3488
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 OP (SIDING SPRING)
     [Editor's note:  this text replaces that on CBET 3486.]
     An apparently asteroidal object found by R. H. McNaught last July on CCD
images taken with the 0.5-m Uppsala Schmidt telescope at Siding Spring
(discovery observations tabulated below) has been found to show cometary
appearance by H. Sato (Tokyo, Japan), who found that images obtained with the
iTelescope 0.51-m f/6.8 astrograph at Siding Spring on Mar. 20.78 UT show a
hint of coma 10" in diameter of V-band magnitude 18.9 as measured within a
circular aperture of radius 6".5 on three stacked 60-s images; stacked frames
with the same telescope on Apr. 11.4 show a strongly condensed coma 12" in
diameter.  Sato's stacked images taken on Apr. 9.4 with an iTelescope 0.43-m
f/6.8 astrograph near Mayhill, NM, U.S.A., show a strongly condensed coma 10"
in diameter with a fan-like tail 10"-20" long toward p.a. 160 degrees.
L. Buzzi used fourteen stacked 60-s images taken with the 2.0-m "Faulkes
Telescope North" on Apr. 19.5 to find a softer aspect with respect to stars,
with a coma at least 4" wide possibly elongated toward the west.  W. Ryan
(2.4-m f/8.9 reflector + VR filter at the Magdalena Ridge Observatory)
writes that two sets of images taken on Apr. 22.42 and 22.45 in approximately
1" seeing show that the object clearly has an asymmetric coma/tail oriented
toward p.a. about 250 deg even in single images (but becomes more apparent
when stacked).  The object was originally announced on MPEC 2012-O12 and
given the minor-planet designation 2012 OP.

     2012 UT             R.A. (2000) Decl.       Mag.   Observer
     July 16.62216   19 11 03.20   -65 18 37.4   20.0   McNaught
          16.63506   19 10 59.93   -65 18 29.6   19.8     "
          16.64817   19 10 56.44   -65 18 22.0            "
          16.66105   19 10 53.10   -65 18 13.7   20.2     "
          16.67303   19 10 49.99   -65 18 06.0   20.1     "
          16.74880   19 10 30.17   -65 17 18.2   19.6     "
          16.75391   19 10 28.83   -65 17 14.8   19.9     "

The available astrometry, the following orbital elements by G. V. Williams
(from 64 observations spanning 2012 July 16-2013 Apr. 19; mean residual 0".3),
and an ephemeris appear on MPEC 2013-H36.

                    Epoch = 2012 Dec. 19.0 TT
     T = 2012 Dec.  4.74202 TT        Peri. = 351.43541
     e = 0.9966160                    Node  = 267.37058 2000.0
     q = 3.6071110 AU                 Incl. = 114.82820


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

                         (C) Copyright 2013 CBAT
2013 April 23                    (CBET 3488)              Daniel W. E. Green