Electronic Telegram No. 4335
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 U1 (NEOWISE)
     Joseph R. Masiero and James M. Bauer, Jet Propulsion Laboratory, report
that a comet with a clear coma was detected on infrared images taken on Oct.
21 and 22 with the Near-Earth Object Wide-field Infrared Survey Explorer (or
NEOWISE; formerly the WISE earth-orbiting satellite; cf. CBET 4225).  The
discovery observations are tabulated below, in which the listed optical-
wavelength magnitude was roughly estimated as 19 based on past WISE and
NEOWISE cometary observations.

     2016 UT             R.A. (2000) Decl.
     Oct. 21.29261    8 39 28.27   +45 42 17.9
          21.68557    8 40 51.66   +45 47 37.1
          21.81660    8 41 19.70   +45 49 22.4
          22.01309    8 42 01.89   +45 52 02.1
          22.27515    8 42 58.16   +45 55 39.2
          22.34060    8 43 12.41   +45 56 36.5
          22.40618    8 43 26.89   +45 57 26.0
          22.53708    8 43 55.28   +45 59 15.2

Additional NEOWISE images of the comet taken on Oct. 27, 28, and 29 show it
to be of similar brightness and again notably extended.  The object was
posted on the Minor Planet Center's PCCP webpage.  D. J. Tholen writes
that CCD images of the comet obtained on Oct. 28.6 UT by C. Wipper with the
3.6-m Canada-France-Hawaii Telescope at Mauna Kea yield red mag 22.5, but
the comet's proximity to a nearby 7th-mag star in sub-standard seeing
prevented definite discernment of cometary appearance; however, Tholen adds
that follow-up observations obtained by Y. Ramanjooloo on Nov. 2.6 with the
2.24-m University of Hawaii reflector in better seeing show a short, stubby
tail extending about 5" in position angle 294 deg (with the fitted point-
spread-function width being 1".24 for the comet, compared to 0".83 for
nearby star trails).  H. Sato, Tokyo, Japan, notes that ten stacked 20-s
exposures taken on Oct. 25.5 with a 0.61-m f/6.5 astrograph (+ luminance
filter) at the Sierra Remote Observatory, Auberry, CA, USA, show it to be
weakly condensed with a fuzzy coma 6" in diameter and no tail; the w-band
magnitude was 20.1 as measured within a circular aperture of radius 3".8.
     Astrometry, the following preliminary parabolic orbital elements by
G. V. Williams, and an ephemeris appear on MPEC 2016-V16.

     T = 2017 Jan. 14.0251 TT         Peri. = 162.7618
                                      Node  =  61.4172  2000.0
     q = 0.319189 AU                  Incl. =  46.4258


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

                         (C) Copyright 2016 CBAT
2016 November 3                  (CBET 4335)              Daniel W. E. Green