Electronic Telegram No. 4362
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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Prepared using the Tamkin Foundation Computer Network


COMET C/2017 C2 (PANSTARRS)
     E. Lilly and R. Weryk, Institute for Astronomy, University of Hawaii,
report the discovery of another comet on CCD i-band images obtained with the
1.8-m Pan-STARRS1 telescope at Haleakala on Feb. 4 (discovery observations
tabulated below), the object showing a soft appearance, with full-width-at-
half-maximum of approximately 1".7, compared to adjacent stars that had FWHM
of 1".2; though there is no clear evidence for a tail, the object appears
asymmetric in shape.

     2017 UT             R.A. (2000) Decl.       Mag.
     Feb.  4.25802    3 05 52.44   +58 09 23.9   19.6
           4.27204    3 05 52.40   +58 08 45.2   19.7
           4.28603    3 05 52.33   +58 08 06.3   19.7

After the object was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists have also noted the cometary appearance.  H. Sato, Tokyo,
Japan, writes that sixteen stacked 45-s exposures taken on Feb. 6.10 UT with
an iTelescope 0.51-m f/6.8 astrograph (+ luminance filter) near Mayhill, NM,
USA, show a strongly condensed coma 6" in diameter with a hint of a tail 8"
long toward p.a. 120 degrees; the w-band magnitude was 19.7 as measured
within a circular aperture of radius 4".9.  G. Baj, Varese, Italy, note that
stacked images taken on Feb. 17.8 with a 0.30-m f/8 Ritchey-Chretien reflector
at Saltrio, Italy, in good seeing show the object to be clearly cometary,
with a compact coma and a weak tail 4".9 long in p.a. 134.1 degrees.
     The available astrometry, the following elliptical orbital elements by
G. V. Williams, and an ephemeris appear on MPEC 2017-D22.

                    Epoch = 2017 Jan.  7.0 TT
     T = 2017 Jan. 21.5494 TT         Peri. = 138.7443
     e = 0.979112                     Node  = 249.8085  2000.0
     q = 2.431749 AU                  Incl. = 118.5825


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2017 CBAT
2017 February 20                 (CBET 4362)              Daniel W. E. Green