[Iaude] CBET 4317: 20160909 : COMET C/2016 P4 (PANSTARRS)

quai at eps.harvard.edu quai at eps.harvard.edu
Thu Sep 8 17:11:26 EDT 2016


                                                  Electronic Telegram No. 4317
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 C/2016 P4 (PANSTARRS)
     R. J. Wainscoat reports the discovery of an apparent comet in exposures
obtained with the 1.8-m Pan-STARRS1 telescope at Haleakala on Aug. 7 UT
(discovery observations tabulated below, along with pre-discovery images from
July 31); the object appears slightly soft in the discovery images, though
very faint, with the presumed comet having an image in co-added exposures that
appeared 0".25 larger than that of adjacent stars (1".0 seeing).

     2016 UT             R.A. (2000) Decl.       Mag.
     July 31.42747   21 03 23.37   -23 57 47.7   21.7
          31.43781   21 03 23.06   -23 57 46.6   22.5
          31.44815   21 03 22.75   -23 57 45.9   22.0
     Aug.  7.39742   21 00 03.66   -23 46 20.4   21.7
           7.41937   21 00 03.00   -23 46 18.2   21.8
           7.43033   21 00 02.68   -23 46 17.1   21.8
           7.43204   21 00 02.63   -23 46 16.9   22.0
           7.44393   21 00 02.29   -23 46 15.7   22.0
           7.45587   21 00 01.92   -23 46 14.5   22.0
           7.46781   21 00 01.59   -23 46 13.1   22.0

Wainscoat writes that he obtained three 60-s w-band follow-up exposures using
the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea on Sept. 7.3 UT, which
show that the comet appears to be soft relative to adjacent stars (FWHM about
0".9, compared to about 0".7 for nearby stars); M. Micheli measured the images
and found red mag 21.7-21.9, agreeing that the point-spread function (PSF)
seems to be slightly larger than that for nearby stars, suggesting some weak
activity.  D. J. Tholen notes that images taken on Aug. 8.45 by D. Hung and
Y. Ramanjooloo with the 2.24-m University of Hawaii reflector also show a
fitted PSF that is about 0".25 wider than for nearby stars, adding that the
PSF width is also dependent on the size of the synthetic aperture used for
the fitting, which is a cometary attribute; the red magnitude was given as
21.7-21.8.  Stacked CCD images taken by R. A. Mastaler on Aug. 29.20-29.26
with the Spacewatch 1.8-m telescope at Kitt Peak show a diffuse object with
red mag 21.1-21.7.
     The available astrometry, the following highly elliptical orbital
elements by G. V. Williams (from 34 observations spanning July 31-Sept. 7),
and an ephemeris appear on MPEC 2016-R88.

                    Epoch = 2016 Oct. 19.0 TT
     T = 2016 Oct. 16.6432 TT         Peri. = 356.0166
     e = 0.982119                     Node  = 320.7940  2000.0
     q = 5.888697 AU                  Incl. =  29.9013


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

                         (C) Copyright 2016 CBAT
2016 September 9                 (CBET 4317)              Daniel W. E. Green




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