Electronic Telegram No. 4355
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)
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Prepared using the Tamkin Foundation Computer Network


COMET P/2017 B4 (PANSTARRS)
     Eva Lilly, Richard Wainscoat, and Rob Weryk, Institute for Astronomy,
University of Hawaii, report the discovery of another comet on CCD images
obtained with the 1.8-m Pan-STARRS1 telescope at Haleakala on Jan. 28
(discovery observations tabulated below), the object showing a larger FWHM
than images of adjacent stars and appearing slightly asymmetric, suggesting
a short tail towards the west.

     2017 UT             R.A. (2000) Decl.       Mag.
     Jan. 28.38604    9 48 15.12   +22 20 21.3   21.2
          28.39835    9 48 14.72   +22 20 29.5   21.2
          28.41052    9 48 14.33   +22 20 38.1   21.3

M. Micheli reports that three 60-s follow-up exposures images taken by R. J.
Wainscoat and D. Woodworth with the 3.6-m Canada-France-Hawaii Telescope (with
g, r, and i filters) on Jan. 29.36 UT show the object to be clearly cometary,
with a coma with FWHM 1".0 (in 0".8 seeing) and a tail about 10" long in p.a.
270 deg.
     After the object was posted on the Minor Planet Center's PCCP webpage,
H. Sato (Tokyo, Japan) reported twenty stacked exposures obtained with an
iTelescope 0.51-m f/6.8 astrograph (+ luminance filter) near Mayhill, NM,
USA, on Jan. 30.28 that show a moderately condensed coma 8" in diameter and
no tail; the w-band magnitude was 20.2 as measured within a circular aperture
of radius 4".9.
     The available astrometry, the following preliminary elliptical orbital
elements by G. V. Williams (from 44 observations spanning Jan. 28-Feb. 3),
and an ephemeris appear on MPEC 2017-C46.

     T = 2017 Jan. 12.4955 TT         Peri. =  13.0974
     e = 0.364952                     Node  = 120.7382  2000.0
     q = 2.743596 AU                  Incl. =  19.1628
       a =  4.320294 AU    n = 0.1097575    P =   8.98 years


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2017 CBAT
2017 February 4                  (CBET 4355)              Daniel W. E. Green