[IAUC] CBET 3345: 20121216 : COMET C/2012 X2 (PANSTARRS)

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3345
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 en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2012 X2 (PANSTARRS)
     [Editor's note:  this text replaces that on CBET 3343 (reference).]
     Henry Hsieh, Larry Denneau, Marco Micheli, Bryce Bolin, and Peter Veres
Institute for Astronomy, University of Hawaii, report the discovery of a
comet on two g-band 43-s exposures and two r-band 40-s exposures taken with
the Pan-STARRS1 telescope on Haleakala (discovery observations tabulated
below); the object is extended with a faint tail spanning p.a. 90-140 deg.
After posting on the Minor Planet Center's NEOCP webpage, numerous other CCD
astrometrists have also commented on the object's cometary appearance.  H.
Sato (Tokyo, Japan; obtained remotely with a 0.43-m f/6.8 astrograph at the
iTelescope Observatory near Mayhill, NM, U.S.A.; Dec. 13.24-13.25 UT) notes
that twelve stacked 60-s exposures show a strongly condensed, round coma 10"
in diameter with total V-band magnitude 18.9 as measured within a circular
aperture of radius 5".7.  William H. Ryan (Magdalena Ridge Observatory; 2.4-m
f/8.9 reflector; Dec. 13.3) finds a distinct coma of red mag 18.2 and tail in
p.a. about 315 deg on four R-band images.  D. J. Tholen writes that images
obtained by M. Micheli and G. T. Elliott with the 2.24-m University of Hawaii
reflector at Mauna Kea on Dec. 13.5-13.6 show an asymmetric coma and a tail
extending as much as 40" to the northwest.  Forty-five co-added 30-s images
taken by T. Linder and R. Holmes with a 0.41-m f/11 Ritchey-Chretien
reflector at Cerro Tololo on Dec. 14.2 show a round coma of diameter 4".5;
their subsequent set of similar stacked images on Dec. 15.2 show a coma of
size 4" x 6" elongated toward p.a. 250 deg, with a 3" tail in p.a. 310 deg.
T. Lister reports that five stacked 300-s images taken with a 1.0-m f/8
Ritchey-Chretien reflector (Las Cumbres Observatory Global Telescope) at
Cerro Tololo on Dec. 14.3 in 1".5 seeing show a central condensation with a
coma of size about 5" and a tail about 30" long in p.a. 135 deg.  Forty-five
stacked 60-s exposures taken by R. Holmes (Ashmore, IL, USA; 0.61-m f/4
astrograph; Dec. 14.3; purportedly measured by four different people -- L.
Buzzi, H. Devore, S. Foglia, and T. Vorobjov) show a coma of size 8" x 12",
elongated in p.a. 310 degrees with a tail 30" long toward that position angle.
Detlef Koschny, European Space Agency (ESA), Noordwijk, writes that images
taken on Dec. 15.95-15.96 with a 1.0-m f/4.4 reflector at the ESA Optical
Ground Station, Tenerife, by P. Ruiz (measured by Koschny, M. Busch, A.
Knoefel, and E. Schwab) shows the comet to be elongated with a 10" tail in
p.a. 300 deg.

     2012 UT             R.A. (2000) Decl.       Mag.
     Dec. 12.52892    7 43 03.66   + 6 29 07.9   20.0
          12.54241    7 43 03.35   + 6 29 03.0   20.0
          12.55557    7 43 03.04   + 6 28 58.4   19.6
          12.56790    7 43 02.75   + 6 28 54.0   19.6

The available astrometry, the following preliminary parabolic orbital elements
by G. V. Williams, and an ephemeris appear on MPEC 2012-Y01.

     T = 2013 Oct. 29.9103 TT         Peri. = 244.2691
                                      Node  = 273.7298  2000.0
     q = 4.374599 AU                  Incl. =  38.0016


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

                         (C) Copyright 2012 CBAT
2012 December 16                 (CBET 3345)              Daniel W. E. Green