Electronic Telegram No. 4227
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)
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Prepared using the Tamkin Foundation Computer Network


COMET C/2015 Y1 (LINEAR)
     An apparently asteroidal object found on CCD images taken on Dec. 16
with the 3.5-m f/1 Space Surveillance Telescope on Atom Peak in the White
Sands Missile Range, NM, USA, in the course of the LINEAR survey (discovery
observations tabulated below) has been found to show cometary appearance by
CCD astrometrists elsewhere after the object was posted on the Minor Planet
Center's NEOCP and PCCP webpages.

     2015 UT             R.A. (2000) Decl.       Mag.
     Dec. 16.43041    9 20 41.59   -11 39 11.7   18.3
          16.43564    9 20 41.48   -11 39 09.4   18.3
          16.44059    9 20 41.48   -11 39 06.4   18.3
          16.44541    9 20 41.45   -11 39 03.8   18.5
          16.45019    9 20 41.37   -11 39 01.5   18.2
          16.45501    9 20 41.35   -11 38 58.6   18.5

R-band images obtained by T. Lister, S. Greenstreet, and E. Gomez with a
1.0-m f/8 Ritchey-Chretien reflector at Sutherland, South Africa, on Dec. 18.0
UT show some central condensation and a wedge-shaped tail about 14" long in
p.a. about 270 deg.  Three stacked 60-s exposures taken by H. Sato, Tokyo,
Japan, on Dec. 18.59 with an iTelescope 0.51-m f/6.8 astrograph (+ luminance
filter) at Siding Spring show a strongly consensed coma 8" in diameter (of
w-band magnitude 17.8 as measured within a circular aperture of radius 4".9)
and a 30" tail toward p.a. 280 degrees.  Stacked, unfiltered images taken by
A. Maury and J.-F. Soulier on Dec. 20.3 with a 0.4-m f/8 Ritchey-Chretien
reflector at San Pedro de Atacama, Chile, show an 11" coma and a possible
tail about 1' long in p.a. 295 deg.  R. Ligustri, Udine, Italy, notes a tail
about 12" long in p.a. 320 deg in eight stacked 60-s exposures taken on Dec.
19.6 with an iTelescope 70-cm f/6.4 reflector near Mayhill, NM, USA.  L.
Buzzi, Varese, Italy, notes that stacked images obtained in good seeing on
Dec. 20.1 with a 0.60-m f/4.6 reflector reveal a condensed coma 10" wide and
a broad tail at least 25" long in p.a. 274 deg.  R. Reszelewski, Swidwin,
Poland, finds the comet to be slightly diffuse on images taken on Dec.
20.35-20.36 with a 0.25-m f/3.6 astrograph of the Polonia Observatory at San
Pedro de Atacama by M. Gedek, M. Zolnowski, M. Kusiak, and Reszelewski.
     The available astrometry (spanning Dec. 16-20), the following
preliminary parabolic orbital elements by G. V. Williams, and an ephemeris
appear on MPEC 2015-Y58.

     T = 2016 May  15.9350 TT         Peri. =  25.2437
                                      Node  = 135.7259  2000.0
     q = 2.501999 AU                  Incl. =  71.3379


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

                         (C) Copyright 2015 CBAT
2015 December 21                 (CBET 4227)              Daniel W. E. Green