Electronic Telegram No. 4273
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 WZ (PANSTARRS)
     An apparently asteroidal object that was discovered last year with the
1.8-m Pan-STARRS1 telescope at Haleakala (discovery date being 2015 Nov. 17,
but with numerous other Pan-STARRS1 images also obtained around that time,
as tabulated below), and assigned the minor-planet designation 2015 WZ when
announced on MPEC 2015-W30, has been found to show cometary appearance by
CCD observers elsewhere in just the past week.

     2015 UT             R.A. (2000) Decl.       Mag.
     Oct. 25.46945    4 46 05.75   - 0 53 19.7   21.3
          25.49415    4 46 02.28   - 0 53 23.5   21.9
     Nov.  7.45216    4 09 13.84   - 1 19 50.6   20.2
           8.51323    4 05 36.82   - 1 21 01.6   21.2
           8.52653    4 05 34.05   - 1 21 02.5   20.8
          15.35644    3 40 19.04   - 1 23 12.4   20.8
          15.36910    3 40 16.02   - 1 23 11.8   21.1
          15.38171    3 40 12.99   - 1 23 11.9   21.3
          15.39433    3 40 10.01   - 1 23 11.5   21.0
          17.39614    3 32 11.34   - 1 21 45.5   20.9
          17.40781    3 32 08.48   - 1 21 44.8   20.7
          17.41948    3 32 05.62   - 1 21 44.0   21.0

A. Novichonok, Observatory of Petrozavodsk State University, Petrozavodsk,
Russia, writes that he has measured three unfiltered 90-s images of 2015 WZ
obtained by G. Borisov with the 0.5-m f/2 telescope of MARGO Observatory near
Nauchnij, Crimea, on 2016 Apr. 17.05 UT; the object shows a diffuse,
moderately condensed coma of diameter about 1'.9 with a possible tail 1'.4
long in p.a. 282 deg; the total red magnitude of the comet was 13.0 as
measured in a circular aperture of size 2'.02.  D. Denisenko, Sternberg
Astronomical Institute, Moscow State University, reports that nine unfiltered
60-s exposures taken remotely with an iTelescope 0.51-m f/6.8 astrograph near
Mayfield, NM, USA, on Apr. 20.46 show a coma at least 30" in diameter with
magnitude 14.0; follow-up images obtained on Apr. 22.45 by Denisenko the same
telescope (but with the nearly full moon closer to the comet) show a
moderately condensed 25" coma of mag 14.2.
     The available astrometry, the following nearly-parabolic orbital elements
by G. V. Williams, and an ephemeris appear on MPEC 2016-H29.

                    Epoch = 2016 Apr.  2.0 TT
     T = 2016 Apr. 15.79862 TT        Peri. =  66.71011
     e = 0.9929157                    Node  =  40.04558 2000.0
     q = 1.3766422 AU                 Incl. = 134.13477


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

                         (C) Copyright 2016 CBAT
2016 April 24                    (CBET 4273)              Daniel W. E. Green