[Iaude] CBET 4448: 20171028 : COMET P/2017 S9 (PANSTARRS)

quai at eps.harvard.edu quai at eps.harvard.edu
Fri Oct 27 21:37:04 EDT 2017


                                                  Electronic Telegram No. 4448
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET P/2017 S9 (PANSTARRS)
     R. Weryk, Institute for Astronomy, University of Hawaii, reports the
discovery of another comet on CCD exposures taken with the 1.8-m Pan-STARRS1
telescope at Haleakala on Sept. 30 UT (discovery astrometry tabulated below,
together with pre-discovery Pan-STARRS1 observations from Sept. 19), the
object showing a 10" tail towards the west; the comet's head showed a full-
width-at-half-maximum of about 1".6 in 1".2 seeing.  Weryk then identified
this object with one found on Sept. 19.6 on Pan-STARRS1 exposures, when
there was a much fainter tail extending for about 4" towards the west
(and the head's FWHM was about 1".3 in about 1".2 seeing).

     2017 UT             R.A. (2000) Decl.       Mag.
     Sept.19.60005    4 44 09.25   + 4 17 09.4   21.6
          19.60855    4 44 09.66   + 4 17 06.3   21.9
          19.61707    4 44 10.11   + 4 17 03.1   21.7
          19.62559    4 44 10.55   + 4 17 00.5   21.6
          30.59048    4 52 14.81   + 3 07 06.6   22.0
          30.59126    4 52 14.84   + 3 07 06.4   21.7
          30.60198    4 52 15.19   + 3 07 02.2   21.6
          30.60277    4 52 15.23   + 3 07 01.7   21.5
          30.61351    4 52 15.59   + 3 06 57.3   21.8
          30.61431    4 52 15.62   + 3 06 57.0   21.7
          30.62499    4 52 15.97   + 3 06 52.9   21.7
          30.62579    4 52 15.98   + 3 06 52.5   21.6

R. J. Wainscoat and Weryk report that three 60-s w-band CCD follow-up
exposures obtained by Wainscoat and C. Wipper on Oct. 22.5 UT with the 3.6-m
Canada-France-Hawaii Telescope at Mauna Kea (measured with M. Micheli) show a
broad, low-surface-brightness tail about 10" long to the west.
     After the comet was posted on the Minor Planet Center's PCCP webpage,
other CCD astrometrists also reported cometary appearance.  H. Sato, Tokyo,
Japan, obtained fourteen stacked 60-s exposures with an iTelescope 0.61-m
f/6.5 astrograph at the Sierra Remote Observatory near Auberry, CA, USA, on
Oct. 1.52 UT that show the object elongated westwards with a coma of size
4" x 10"; the total w-band magnitude was 20.5 as measured within a circular
aperture of radius 5".0.  K. Sarneczky, Konkoly Observatory, writes that
twelve stacked 90-s unfiltered CCD images taken with the 1.02-m Ritchey-
Chretien telescope at Piszkesteto, Hungary, on Oct. 15.1 show a nearly
stellar coma with a faint tail 20" long in p.a. 270 deg; the red magnitude
of the coma was 20.8 as measured within a circular aperture of radius 3".0.
     The available astrometry, the following elliptical orbital elements by
G. V. Williams (from 39 observations spanning Sept. 19-Oct. 22), and an
ephemeris appear on MPEC 2017-U237.

                    Epoch = 2017 July 26.0 TT
     T = 2017 July 23.5568 TT         Peri. = 237.8964
     e = 0.304516                     Node  = 146.2136  2000.0
     q = 2.195060 AU                  Incl. =  14.1377
       a =  3.156162 AU    n = 0.1757782    P =   5.61 years


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

                         (C) Copyright 2017 CBAT
2017 October 28                  (CBET 4448)              Daniel W. E. Green



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