Electronic Telegram No. 4238
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/2016 A5 (PANSTARRS)
     R. Wainscoat reported that an object found on images taken on Jan. 9.5
with the 1.8-m Pan-STARRS1 telescope on Haleakala (discovery observations
tabulated below) seem to show a very faint tail slightly south of west, but
very much at the detection limit.  After the object was posted on the Minor
Planet Center's PCCP webpage, CCD astometrists elsewhere commented on the
object's cometary appearance.

     2016 UT             R.A. (2000) Decl.       Mag.
     Jan.  9.49003   10 38 49.13   +16 39 05.0   22.2
           9.50162   10 38 49.11   +16 39 13.3   21.9
           9.51326   10 38 49.07   +16 39 21.6   21.9
           9.52495   10 38 49.05   +16 39 30.0   22.0

H. Sato, Tokyo, Japan (0.70-m f/6.6 astrograph + luminance filter) notes that
eleven stacked 60-s exposures taken on Jan. 10.74 UT show the object to be
moderately condensed with a coma 10" in diameter (magnitude 20.6 as measured
within a circular aperture of radius 5".5) with a hint of a tail 15" long
toward p.a. 25 degrees.  V-band exposures taken by W. H. Ryan and E. V. Ryan
with the Magdalena Ridge Observatory's 2.4-m f/8.9 reflector on Jan. 12.4
show a distinct tail toward p.a. about 250 deg (the comet's magnitude measured
as 20.9-21.1); follow-up exposures on Jan. 14.3 show a long, thin tail in
p.a. about 260 deg.  D. J. Tholen writes that images taken by Y. Ramanjooloo,
R. Weryk, and himself on Jan. 13.48 with the 2.24-m University of Hawaii
reflector at Mauna Kea show a tail extending for perhaps 17" in position
angle about 257 deg; the red magnitude was measured as 21.1.  T. H. Bressi
relates that images taken on Jan. 15.3 with the Spacewatch 1.8-m f/2.7
reflector (+ Schott OG-515 filter; bandpass 515-950 nm) at Kitt Peak show
a 12" tail in p.a. abou t260 deg; the red magnitude was measured to be
20.0-20.3.
     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2016-B09.

     T = 2015 June 28.8486 TT         Peri. = 319.7540
                                      Node  = 135.6304  2000.0
     q = 2.836940 AU                  Incl. =  38.8556


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2016 CBAT
2016 January 16                  (CBET 4238)              Daniel W. E. Green