Electronic Telegram No. 4083
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 F2 (POLONIA)
     Rafal Reszelewski, Swidwin, Poland; and Michal Kusiak, Zywiec, Poland,
report the discovery of a diffuse comet with diameter 7"-10" and no tail on
CCD images (pixel size 3".5) obtained by Marcin Gedek (Oborniki, Poland),
Michal Zolnowski (Krakow, Poland), and themselves on Mar. 23.3 UT (discovery
observations tabulated below) with a remote-controlled 0.1-m f/5 astrograph
of the Polonia Observatory at San Pedro de Atacama, Chile, in the course of
their comet-search program.

     2015 UT             R.A. (2000) Decl.       Mag.
     Mar. 23.29317   18 28 51.82   -51 32 12.8   16.8
          23.29884   18 28 53.95   -51 32 05.1   17.5
          23.30451   18 28 55.91   -51 31 59.6   17.0

After the object was posted on the Minor Planet Center's NEOCP and PCCP
webpages, other CCD astrometrists have commented on its cometary appearance.
H. Sato (Tokyo, Japan; eight 20-s exposures obtained remotely using an
iTelescope 0.70-m f/6.6 astrograph + luminance filter at Siding Spring) found
the comet to be strongly condensed with a round coma 10" in diameter, with
magnitude 16.8 as measured within a circular aperture of radius 5".4 on Mar.
23.76 UT.  E. Guido and N. Howes (fourteen stacked 30-s exposures obtained
remotely using an iTelescope 0.43-m f/6.8 astrograph at Siding Spring) note
an ill-defined central condensation surrounded by a diffuse irregular coma
15" in diameter on Mar. 23.8.  Ten stacked 60-s images taken remotely by C.
Jacques, E. Pimentel, and J. Barros using an iTelescope 0.70-m f/6.6
astrograph at Siding Spring show a diffuse coma with diameter 18", slightly
elongated towards p.a. 263 deg.  E. Bryssinck, Kruibeke, Belgium, stacked
nine 60-s images taken remotely on Mar. 26.7 with a Tzec Maun 0.15-m f/7.2
refractor at Siding Spring, revealing a diffuse object with central
condensation and a coma diameter of 33".
     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2015-F120.

     T = 2015 Apr. 28.7729 TT         Peri. = 351.9757
                                      Node  = 262.8944  2000.0
     q = 1.215539 AU                  Incl. =  28.8750


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2015 CBAT
2015 March 27                    (CBET 4083)              Daniel W. E. Green