Electronic Telegram No. 4071
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/2015 D4 (BORISOV)
     Gennady Borisov, Nauchnij, Crimea, reports his discovery of a comet on
three CCD images taken with a 0.3-m f/1.5 astrograph on Feb. 23.1 UT
(discovery observations tabulated below).

     2015 UT             R.A. (2000) Decl.       Mag.   Observer
     Feb. 23.10458   21 08 51.59   +22 47 18.5   16.8   Borisov
          23.11875   21 08 53.11   +22 47 42.4   16.9     "
          23.13194   21 08 54.48   +22 48 04.4   16.9     "
          25.09792   21 11 27.68   +23 37 56.2   17.4     "
          25.13055   21 11 30.06   +23 38 46.9   17.5     "

After the object was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists have commented on the object's cometary appearance.
V. Nevski writes that xix stacked 60-s exposures taken with a 0.4-m reflector
at the ISON-Byurakan Observatory in Armenia on Feb. 26.1 show a coma 12" in
diameter and a 30" tail in p.a. 185 deg.  H. Sato, Tokyo, Japan, reports that
ten stacked 60-s exposures taken with an iTelescope 0.51-m f/6.8 astrograph
(+ luminance filter) near Mayhill, NM, USA, on Mar. 1.5 show the comet to be
moderately condensed with an elongated coma of size 10" x 15" (magnitude 17.7
as measured within a circular aperture of radius 8".2) and a hint of a tail
40" long toward p.a. 195 degrees.
     The available astrometry, preliminary parabolic orbital elements by G. V.
Williams, and an ephemeris appear on MPEC 2015-E08.

     T = 2014 Oct. 31.0668 TT         Peri. = 312.7192
                                      Node  = 305.6626  2000.0
     q = 0.810813 AU                  Incl. =  77.2920


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2015 CBAT
2015 March 2                     (CBET 4071)              Daniel W. E. Green