Electronic Telegram No. 3584
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/2013 N4 (BORISOV)
     Gennady Borisov, Crimean Laboratory of the Sternberg Astronomical
Institute, reports the discovery of a comet on three CCD images taken with a
0.2-m f/1.5 astrograph on July 8.99 UT, the object displaying a coma of
diameter about 20"; the initial astrometry is tabulated below.  A. Novichonok
adds that ten follow-up 180-s exposures taken by I. Ionov with the Crimean
0.32-m f/4 Newtonian reflector on July 11.0 show a large, diffuse, round
coma of diameter 1'.7 and total mag near 13.5 but with no visible tail.
After posting on the Minor Planet Center's NEOCP webpage, other CCD
astrometrists have also noted the object's cometary appearance.  P.
Birtwhistle (Great Shefford, Berkshire, England; 0.40-m f/6 Schmidt-Cassegrain
reflector; July 12.1) finds a central condensation of diameter 6" surrounded
by a faint coma of size 25" x 35" (and total mag 15.2), elongated in p.a.
135/315 degrees; the magnitude was 15.2 as measured in an aperture of diameter
34" and 16.1-16.5 as measured in an aperture of diameter 12".8.  Four stacked
60-s CCD exposures taken by E. Romas, V. Nevski, O. Zelyoniy, and A. Porfir'ev
with a 0.25-m reflector at the ISON-Kislovodsk Observatory in Russia on July
11.99 show a coma of diameter 2'.  H. Sato (Tokyo, Japan; remotely using an
iTelescope.net 0.51-m f/6.8 astrograph located near Mayhill, NM, U.S.A., on
July 12.46) found a bright, strongly condensed coma of diameter 1'.0 with
V-band magnitude 12.9 as measured within a circular aperture of radius 32".8;
images taken on July 13.4 as on the previous night by Sato show similar
appearance, but the magnitude was 13.9 in the same-sized aperture.  R. Ligustri
(Talmassons, Udine, Italy; remotely with a 0.50-m f/4.5 reflector of
iTelescope.net located near Mayhill) noted a coma diameter of about 16" in
twilight.  K. Kadota (Ageo, Saitama, Japan; 0.25-m f/5 reflector; July 12.77;
through clouds) finds a coma of total mag 13.5 and diameter 0'.6 with no tail.
     A. Hale, Cloudcroft, NM, U.S.A., reports total visual mag 13.5
(corrected for atmospheric extinction) with a diffuse 0'.6 coma as seen
vaguely at low altitude with a 0.41-m reflector on July 12.44.

     2013 UT             R.A. (2000) Decl.       Mag.   Observer
     July  8.98688    5 36 12.45   +45 34 24.4   16.8   Borisov
           8.99692    5 36 16.10   +45 34 23.0   16.8     "
           9.00769    5 36 19.67   +45 34 21.3   16.8     "
           9.99716    5 41 37.69   +45 29 13.1   16.8     "
          10.00148    5 41 38.80   +45 29 14.0   16.8     "
          10.00503    5 41 40.21   +45 29 15.1   16.8     "
          10.00838    5 41 41.49   +45 29 11.0   16.8     "
          10.01759    5 41 44.40   +45 29 08.7   16.8     "
          10.02778    5 41 47.66   +45 29 05.9   16.8     "

The available astrometry, the following parabolic orbital elements
by G. V. Williams, and an ephemeris appear on MPEC 2013-N51.

     T = 2013 Aug. 20.1315 TT         Peri. = 140.8282
                                      Node  = 322.5675  2000.0
     q = 1.225524 AU                  Incl. =  36.9970


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

                         (C) Copyright 2013 CBAT
2013 July 13                     (CBET 3584)              Daniel W. E. Green