Electronic Telegram No. 4143
Central Bureau for Astronomical Telegrams
Mailing address:  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/2015 R3 (PANSTARRS)
     Richard Wainscoat reports the discovery of a comet in four w-band
exposures taken with the 1.8-m Pan-STARRS1 telescope at Haleakala on Sept.
12.6 UT (discovery observations tabulated below), noting that the object is
very faint and passed close to a background star during the sequence of
images; in each image, the object appears to have a faint, low-surface-
brightness extension to the south.

     2015 UT             R.A. (2000) Decl.       Mag.
     Sept.12.57851    3 11 12.51   -13 54 59.3   22.3
          12.58984    3 11 12.21   -13 54 59.9   22.2
          12.60113    3 11 11.91   -13 55 00.4   22.2
          12.61245    3 11 11.62   -13 55 01.3   22.4

After the object was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists have also noted the object's cometary appearance.  Images
taken by R. Holmes, Ashmore, IL, USA, with a 1.3-m f/4 astrograph on Sept.
14.4 UT show a short, narrow tail 8.6" long extending toward p.a. 185.5 deg.
H. Sato, Tokyo, Japan, writes that twenty 60-s exposures taken with an
iTelescope 0.51-m f/6.8 astrograph at Siding Spring on Sept. 14.7 show the
comet to be strongly condensed with a coma 6" in diameter, with a possible
25" tail toward p.a. 40 degrees; the w-band magnitude was 20.8 as measured
within a circular aperture of radius 6".6.
     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2015-S02.

     T = 2014 Feb. 12.7732 TT         Peri. = 276.2466
                                      Node  =  35.2781  2000.0
     q = 5.244245 AU                  Incl. =  86.1731


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2015 CBAT
2015 September 16                (CBET 4143)              Daniel W. E. Green