Electronic Telegram No. 4398
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/2017 K5 (PANSTARRS)
     E. Lilly, R. J. Wainscoat, and M. Micheli report the discovery of another
faint comet in CCD exposures taken with the 1.8-m Pan-STARRS1 telescope at
Haleakala (discovery images tabulated below), the object having an extended
but very soft appearance.

     2017 UT             R.A. (2000) Decl.       Mag.
     May  27.46475   18 04 39.32   +45 18 24.9   22.0
          27.47857   18 04 38.94   +45 18 24.8   22.0
          27.49243   18 04 38.54   +45 18 24.7   22.4
          27.50625   18 04 38.13   +45 18 25.0   22.1

Wainscoat and C. Wipper obtained three 60-s w-band exposures with the 3.6-m
Canada-France Hawaii Telescope at Mauna Kea on May 28.4 UT, which show that
the object is clearly extended, with an unusual appearance:  asymmetric and
extended to the north (FWHM 1".8, compared to adjacent stars with FWHM 0".6);
the magnitude was measured to be 21.2-21.4.
     The available astrometry, the following very preliminary parabolic
orbital elements by G. V. Williams (from 17 observations spanning May 27-
June 1), and an ephemeris appear on MPEC 2017-L05.

     T = 2020 Mar.  5.7520 TT         Peri. = 171.4603
                                      Node  = 103.4566  2000.0
     q = 7.611973 AU                  Incl. =  81.7165


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2017 CBAT
2017 June 1                      (CBET 4398)              Daniel W. E. Green