Electronic Telegram No. 4153
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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Prepared using the Tamkin Foundation Computer Network


COMET C/2015 T4 (PANSTARRS)
     R. Weryk, Institute for Astronomy, University of Hawaii reports the
discovery of a possible comet in three w-band exposures taken with the 1.8-m
Pan-STARRS1 telescope at Haleakala on Oct. 14 UT (discovery observations
tabulated below), noting that there is evidence of a faint tail extending for
approximately 10" towards position angle approximately 300 degrees.

     2015 UT             R.A. (2000) Decl.       Mag.
     Oct. 14.53389    5 54 11.86   + 3 03 23.5   19.2
          14.54689    5 54 11.65   + 3 03 09.3   19.1
          14.55993    5 54 11.44   + 3 02 54.9   19.0

After the object was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists have also noted the object's cometary appearance.  Three
stacked 60-s exposures taken by C. Jacques, E. Pimentel, and J. Barros with a
0.45-m f/2.9 reflector at the SONEAR Observatory, Oliveira, Brazil, on Oct.
15.3 UT show a condensed coma 13" in diameter.  H. Sato, Tokyo, Japan, writes
that ten stacked 60-s exposures taken with an iTelescope 0.51-m f/6.8
astrograph near Mayhill, NM, USA, on Oct. 15.3 show the comet to be strongly
condensed with a coma 8" in diameter and no tail; the w-band magnitude was 18.2
as measured within a circular aperture of radius 4".9.  V-band images taken by
W. H. Ryan and E. V. Ryan with the Magdalena Ridge Observatory 2.4-m f/8.9
reflector on Oct. 15.44-15.46 show a tail in p.a. about 315 deg; the magnitude
was measured as 19.0-19.1.  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.
16.2 show a 14" coma and a likely tail 13" long toward p.a. 290 deg; they
measured the magnitude to be 18.4 in an aperture of radius 7".2 centered on
the nuclear condensation.
     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2015-U3.

     T = 2016 June  2.6594 TT         Peri. = 291.8269
                                      Node  = 251.4970  2000.0
     q = 1.520277 AU                  Incl. =  90.2216


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      superseded by text appearing later in the printed IAU Circulars.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 4153)              Daniel W. E. Green