Electronic Telegram No. 3990
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2014 S3 (PANSTARRS)
     An apparently asteroidal object found with the 1.8-m Pan-STARRS1
telescope at Haleakala on Sept. 22, when it was posted on the Minor Planet
Center's NEOCP webpage (discovery observations tabulated below), has been
reported by R. J. Wainscoat to show cometary appearance on r-band CCD images
taken by P. Forshay and himself on subsequent nights with the 3.6-m Canada-
France-Hawaii Telescope at Mauna Kea.  Analysis by M. Micheli and Wainscoat of
images from Sept. 23.6 UT (tracked at the motion of the comet) show a very
compact, almost starlike core, with a faint, diffuse emission around it,
extending to the west.  Three 150-s exposures taken on Sept. 24.6 show a
starlike nuclear condensation surrounded by a very-low-surface-brightness
halo of light; the halo is asymmetric, extending for 2" to the east and 4" to
the west, though examination was hampered by a nearby low-surface-brightness
background galaxy and a diffraction spike from a nearby bright star, to which
Wainscoat adds that the evidence of cometary activity is subtle.  Four stacked
additional images obtained on Sept. 26.6 show the starlike core and the
asymmetric low-surface-brightness emission extending mostly to the west for
approximately 3".

     2014 UT             R.A. (2000) Decl.       Mag.
     Sept.22.52432    4 43 42.66   +11 29 25.4   21.5
          22.53657    4 43 40.34   +11 29 17.1   21.6
          22.54884    4 43 37.99   +11 29 08.9   21.6
          22.56110    4 43 35.64   +11 29 00.6   21.7

After the object was posted on the Minor Planet Center's PCCP webpage, H. Sato
(Tokyo, Japan) writes that thirty-two stacked 30-s CCD exposures taken with an
iTelescope 0.51-m f/6.8 astrograph (+ luminance filter) at Siding Spring on
Sept. 26.7 shows a moderately condensed coma 8" in diameter with w-band
magnitude 20.5 as measured within a circular aperture of radius 6".5 and no
tail.
     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2014-S114.

     T = 2014 Aug. 15.2973 TT         Peri. = 293.8746
                                      Node  = 355.9407  2000.0
     q = 2.057451 AU                  Incl. = 169.3378


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

                         (C) Copyright 2014 CBAT
2014 September 27                (CBET 3990)              Daniel W. E. Green