Electronic Telegram No. 4152
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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Prepared using the Tamkin Foundation Computer Network


COMET P/2015 T3 (PANSTARRS)
     R. Weryk and E. Lilly report the discovery of another comet in four
w-band exposures taken with the 1.8-m Pan-STARRS1 telescope at Haleakala on
Oct. 13 UT (discovery observations tabulated below).  The object shows
evidence of a faint-but-broad tail extending towards position angle
approximately 70 degrees for approximately 8".  Weryk adds that a similar
sequence of images taken on Oct. 15.5 shows clear evidence of a tail
extending for approximately 10" towards p.a. approximately 70 degrees.

     2015 UT             R.A. (2000) Decl.       Mag.
     Oct. 13.41042    2 13 57.34   - 6 41 43.1   20.9
          13.42456    2 13 56.69   - 6 41 47.2   20.9
          13.43867    2 13 56.03   - 6 41 51.0   21.2
          13.45277    2 13 55.40   - 6 41 55.1   20.9

M. Micheli writes that three confirming 60-s CCD frames were obtained by R. J.
Wainscoat and C. Wipper with the 3.6-m Canada-France-Hawaii Telescope on Oct.
14.45 UT; measurements by Micheli and Weryk show the comet to show a small,
diffuse, obvious coma (FHWM 1".1 in seeing around 0".9) with a tail about 7"
long in p.a. around 80 deg.  After the object was posted on the Minor Planet
Center's PCCP webpage, other CCD astrometrists have also noted the object's
cometary appearance.  T. H. Bressi obtained R-band images on Oct. 14.25-14.26
with the Spacewatch 1.8-m f/2.7 reflector at Kitt Peak that yield magnitude
19.9-20.2, noting that the nuclear condensation may be extended and that
there appears to be a faint, broad tail centered at p.a. 135 deg.  H. Sato,
Tokyo, Japan, finds a moderately condensed coma 15" in diameter with no tail
in nine stacked 60-s exposures obtained with an iTelescope 0.51-m f/6.8
astrograph at Siding Spring on Oct. 14.5; the w-band magnitude was 18.5 as
measured within a circular aperture of radius 8".8.  Sato adds that twelve
stacked 60-s exposures taken with a 0.43-m f/6.8 astrograph at the same
location on Oct. 14.7 also shows a moderately condensed coma 15" in diameter
with mag 18.8 in a circular aperture of radius 7".7.  A. C. Gilmore and P. M.
Kilmartin obtained stacked exposures with the Mt. John 1.0-m f/7.7 reflector
on Oct. 14.5, which reveal a condensed coma with FWHM 2".7 and a tail 5" long
in p.a. 80 degrees.  Images taken by A. Maury and J.-F. Soulier with a 0.4-m
f/8 Ritchey-Chretien reflector at San Pedro de Atacama, Chile, on Oct. 15.1
show an 11" coma and a likely tail 9" long "with structure" pointing toward
p.a. 80 deg.
     The available astrometry, the following preliminary elliptical orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2015-U02.

     T = 2014 Dec. 21.7057 TT         Peri. = 178.6330
     e = 0.508181                     Node  = 120.5019  2000.0
     q = 2.127698 AU                  Incl. =  13.0937
       a =  4.326181 AU    n = 0.1095335    P =   9.0 years


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

                         (C) Copyright 2015 CBAT
2015 October 16                  (CBET 4152)              Daniel W. E. Green