Electronic Telegram No. 4269
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 P/2016 G1 (PANSTARRS)
     R. Weryk and R. J. Wainscoat report the discovery of a comet on four
r-band CCD exposures taken on Apr. 1 UT with the 1.8-m Pan-STARRS1 telescope
at Haleakala (discovery observations tabulated below); there is clear
evidence of a tail extending for approximately 20" towards p.a. approximately
275 degrees; nearby star images are smaller (0".9 FWHM) than images of the
comet (FWHM approximately 1".8).

     2016 UT             R.A. (2000) Decl.       Mag.
     Apr.  1.52835   15 38 01.81   -14 52 06.5   20.1
           1.53967   15 38 01.72   -14 52 02.3   20.0
           1.55105   15 38 01.61   -14 51 58.3   20.1
           1.56239   15 38 01.51   -14 51 53.7   20.4

M. Micheli and Wainscoat further write that three 60-s follow-up exposures
were taken using the 3.6-m Canada-France-Hawaii Telescope (with g, r, and i
filters) at Mauna Kea on Apr. 2.48 UT (queue observer C. Wipper), which show
a well-defined 12" or 15" tail at p.a. 275 deg and a diffuse coma (with FWHM
about 1".9, compared to 0".7 for nearby stars) with measured red magnitude
19.1.  After the object was posted on the Minor Planet Center's PCCP webpage,
other CCD astrometrists elsewhere also commented on its cometary appearance.
K. Sarneczky, Konkoly Observatory, reports that nine stacked 120-s unfiltered
images taken with the 0.60-m Schmidt telescope at the Piszkesteto Station of
Konkoly Observatory on Apr. 4.1 show a condensed coma and a 10"-long tail in
p.a. about 275 deg; the total magnitude was measured to be 18.8 within a
circular aperture of radius 12".  Eight stacked 60-s exposures taken by H.
Sato, Tokyo, Japan, on Apr. 2.7 with an iTelescope 0.70-m f/6.6 astrograph (+
luminance filter) at Siding Spring show the comet to be strongly condensed
with a compact coma 8" in diameter and a 6" tail toward p.a. 100 degrees; the
w-band magnitude was 18.6 as measured within a circular aperture of radius
4".4.  Images taken by R. A. Kowalski with the Mount Lemmon 1.5-m reflector
on Apr. 3.4 show an elliptical coma of mag 18.6 with a major-axis diameter of
approximately 14" and a short, thin tail 15" long in p.a. 285 deg.
     G. V. Williams identified incidental astrometry of the comet from Mt.
Lemmon on Mar. 12.5 UT, in which the apparently asteroidal object was
measured to have magnitude 18.9-19.2.  The available astrometry (spanning
Mar. 12-Apr. 4), the following elliptical orbital elements, and an ephemeris
appear on MPEC 2016-G72.

                    Epoch = 2017 Jan.  7.0 TT
     T = 2017 Jan. 26.5727 TT         Peri. = 111.1342
     e = 0.206822                     Node  = 204.0352  2000.0
     q = 2.046751 AU                  Incl. =  10.9455
       a =  2.580444 AU    n = 0.2377729    P =   4.15 years


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

                         (C) Copyright 2016 CBAT
2016 April 5                     (CBET 4269)              Daniel W. E. Green