[IAUC] CBET 4099: 20150519 : COMET C/2015 J1 (PANSTARRS)

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 4099
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2015 J1 (PANSTARRS)
     R. Weryk and R. Wainscoat, Institute for Astronomy, University of Hawaii,
report the discovery of another apparent comet in three w-band exposures taken
with the 1.8-m Pan-STARRS1 telescope at Haleakala on May 14.34-14.36 UT
(discovery observations tabulated below); the object shows a very short but
faint tail, extending towards position angle approximately 180 degrees, in
each image.

     2015 UT             R.A. (2000) Decl.       Mag.
     May  14.33583   13 59 43.60   -31 55 22.3   20.4
          14.35435   13 59 42.93   -31 55 10.7   20.8
          14.36360   13 59 42.58   -31 55 05.3   20.8

Wainscoat adds that three 60-s r-band follow-up exposures were taken of the
object with the 3.6-m Canada-France-Hawaii Telescope on May 15.4 UT (queue
observer D. Woodworth; measured by Micheli and Wainscoat), which show the
object clearly cometary in appearance, with a long, low-surface-brightness
tail that extends for at least 30" towards p.a. approximately 195 degrees.
E. Lilly and R. Weryk analyzed four additional w-band Pan-STARRS1 images
taken on May 18.4, which again show evidence of a faint tail, extending for
approximately 4".5 towards p.a. approximately 180 degrees.
     After the comet was posted on the Minor Planet Center's PCCP webpage,
other CCD astrometrists have also noted the object's cometary appearance.
H. Sato, Tokyo, Japan, writes that ten stacked 60-s exposures taken with an
iTelescope 0.51-m f/6.8 astrograph (+ luminance filter) at Siding Spring on
May 15.6 UT show the comet to be strongly condensed with a coma 10" in
diameter and no tail; the w-band magnitude was 20.4 as measured within a
circular aperture of radius 6".5.  A. Maury and J.-F. Soulier finds that
images taken on May 16.1 with a 0.4-m f/8 Ritchey-Chretien reflector at San
Pedro de Atacama, Chile, show a 9" coma and a tail 11" long; they measured
the comet's brightness in a 6".2 radius to be 20.0.  W. H. Ryan communicates
that his R-band images taken on May 18.2 with the Magdalena Ridge Observatory
2.4-m f/8.9 reflector show a prominent tail at p.a. about 180 deg, and he
finds the comet's magnitude to be 19.7-19.9.

     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2015-K17.

     T = 2014 July 31.9728 TT         Peri. = 318.7685
                                      Node  = 219.9264  2000.0
     q = 6.120994 AU                  Incl. =  95.2082


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

                         (C) Copyright 2015 CBAT
2015 May 19                      (CBET 4099)              Daniel W. E. Green