Electronic Telegram No. 4260
Central Bureau for Astronomical Telegrams
Mailing address:  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/2016 C2 (NEOWISE)
     J. Bauer, Jet Propulsion Laboratory, reports that another object found on
infrared images taken with the Near-Earth Object Wide-field Infrared Survey
Explorer (or NEOWISE; formerly the WISE earth-orbiting satellite; cf. CBET
4225) suggests the presence of a weak coma.  The discovery observations are
tabulated below, in which the listed optical-wavelength magnitudes were
roughly estimated based on past WISE and NEOWISE cometary observations.

     2016 UT             R.A. (2000) Decl.         Mag.
     Feb.  8.49858   15 13 49.52   - 9 39 24.2     19
           8.76077   15 14 16.40   - 9 46 30.0     19
           8.76090   15 14 16.57   - 9 46 30.7
           8.89193   15 14 29.88   - 9 50 03.0     19
           9.02309   15 14 43.29   - 9 53 38.3
           9.15412   15 14 56.73   - 9 57 14.0
           9.21970   15 15 03.58   - 9 58 58.2
           9.28528   15 15 10.34   -10 00 47.4
           9.48202   15 15 30.59   -10 06 10.6
           9.61305   15 15 44.13   -10 09 44.4
           9.67863   15 15 50.78   -10 11 34.4
           9.74421   15 15 57.64   -10 13 22.5
           9.87524   15 16 11.09   -10 16 56.8
           9.87537   15 16 11.08   -10 16 59.6
          10.00640   15 16 24.48   -10 20 36.4
          10.13756   15 16 38.01   -10 24 12.7
          10.26859   15 16 51.58   -10 27 51.7
          10.26872   15 16 51.53   -10 27 51.1

Bauer also forwards follow-up observations obtained by J. V. Scotti with the
Spacewatch 1.8-m telescope (+ Schott OG-515 filter; bandpass 515-950 nm) on
Feb. 17.5 UT:  thirty stacked 73-s exposures show the comet to be very
slightly diffuse with a coma diameter of 8" and red mag 19.2-19.4, and there
is a very faint tail extending 0'.16 in p.a. 305 degrees.  After the object
was posted on the Minor Planet Center's PCCP webpage, other CCD astrometrists
have also commented on the object's cometary appearance.  V-band images
obtained by W. H. Ryan and E. V. Ryan with the Magdalena Ridge Observatory
2.4-m f/8.9 reflector on Feb. 11.5 and 17.4 both show a faint tail in p.a.
about 315 deg; a fuzzy appearance was noted on Feb. 11.  H. Sato, Tokyo,
Japan, writes that twelve stacked 60-s exposures taken on Feb. 16.8 with a
0.51-m f/6.8 astrograph (+ luminance filter) at Siding Spring show the comet
to be strongly condensed with an asymmetrical outer coma 25" in diameter but
with no tail; the w-band magnitude was 18.0 as measured within a circular
aperture of radius 13".0.
     The available astrometry (spanning Feb. 8-18), the following preliminary
parabolic orbital elements by G. V. Williams, and an ephemeris appear on MPEC
2016-D25.

     T = 2016 Apr. 19.0290 TT         Peri. = 214.0105
                                      Node  =  24.5586  2000.0
     q = 1.567113 AU                  Incl. =  38.1923


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

                         (C) Copyright 2016 CBAT
2016 February 19                 (CBET 4260)              Daniel W. E. Green