Electronic Telegram No. 4386
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 C/2017 G3 (PANSTARRS)
     An apparently asteroidal object found on images obtained on Apr. 7.6 UT
with the 1.8-m Pan-STARRS1 telescope at Haleakala (discovery images tabulated
below) has been found to show cometary appearance on images taken by other
CCD astrometrists elsewhere after the object was posted on the Minor Planet
Center's PCCP webpage.

     2017 UT             R.A. (2000) Decl.       Mag.
     Apr.  7.57471   15 03 26.84   +14 42 11.6   19.6
           7.58392   15 03 24.75   +14 42 29.2   19.7
           7.59311   15 03 22.69   +14 42 46.5   19.6
           7.60231   15 03 20.63   +14 43 04.0   19.5

H. Sato (Tokyo, Japan) writes that twenty stacked 60-s exposures taken on
Apr. 16.2 UT with an iTelescope 0.51-m f/6.8 astrograph near Mayhill, NM, USA,
show a strongly condensed coma 6" in diameter with a narrow tail 20" long
toward p.a. 80 degrees; the total w-band magnitude was 19.5 as measured
within a circular aperture of radius 4".9.  R. Wainscoat reports that three
60-s w-band exposures were obtained on Apr. 20 with the CFHT at Mauna Kea
(queue observer L. Wells), which show that the object has a distinct tail
extending towards position angle approximately 155 degrees for approximately
8"; the core of the object is point-like, with similar FWHM to adjacent stars
(approximately 0".60).  Fifteen stacked 60-s unfiltered images taken by G.
Favero and R. Furgoni with a 0.80-m f/4 reflector at the Osservatorio del
Celado, Castello Tesino, Italy, on Apr. 20.8 show a diffuse appearance and a
clear elongation of about 9" toward p.a. 315 deg; the red magnitude was given
as 19.4-19.5.
     The available astrometry, the following elliptical orbital elements by
G. V. Williams (from 98 observations spanning Apr. 7-20; mean residual 0".4),
and an ephemeris appear on MPEC 2017-H42.

                    Epoch = 2017 Mar. 28.0 TT
     T = 2017 Apr. 15.0153 TT         Peri. =  73.0804
     e = 0.989511                     Node  = 279.4614  2000.0
     q = 2.590245 AU                  Incl. = 159.0518


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2017 CBAT
2017 April 21                    (CBET 4386)              Daniel W. E. Green