Electronic Telegram No. 4231
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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Prepared using the Tamkin Foundation Computer Network


COMET P/2015 Y2 (IKEYA-MURAKAMI)
     Further to CBET 4230, additional confirming observations of a secondary
companion (now denoted as component B, with the CFHT astrometry tabulated
below) have been reported.  M. Micheli reports that very faint images of
component B were identified on exposures taken with the 1.8-m Pan-STARRS1
telescope on Haleakala on 2015 Dec. 31.5 and 2016 Jan. 1.5 UT, the object
noted as being a very diffuse smudge with no central condensation (red
magnitudes 21.4 and 21.6 on the two nights, respectively).  Micheli adds
that additional CFHT images taken by R. J. Wainscoat and P. Forshay on Jan.
2.48 again show a tail for component B whose position angle does not match
that of component A.

     2016 UT             R.A. (2000) Decl.       Mag.   Observer
     Jan.  1.48387    9 11 50.25   +35 57 19.5   20.9   Wainscoat
           1.48514    9 11 50.25   +35 57 19.7   20.8     "
           1.48641    9 11 50.26   +35 57 20.0   20.7     "
           2.47957    9 12 03.22   +36 01 28.2   20.9     "
           2.48119    9 12 03.25   +36 01 28.6   20.7     "
           2.48281    9 12 03.27   +36 01 29.0   20.8     "

H. Sato, Tokyo, Japan, writes that sixteen stacked 60-s exposures taken on
Jan. 3.5 with an iTelescope 0.43-m f/6.8 astrograph (+ luminance filter) near
Mayhill, NM, USA, show component B to be scarcely condensed with a nebulous
coma 15" in diameter (magnitude 19.1 as measured within a circular aperture
of radius 7".6) and a hint of tail 20" long towards p.a. 250 degrees.
Stacked, unfiltered images taken by A. Maury and J.-F. Soulier on Jan. 4.3
with a 0.4-m f/8 Ritchey-Chretien reflector at San Pedro de Atacama, Chile,
show component B to be only about 0.1-0.2 mag fainter than component A (near
magnitude 20); a 9" coma and a 21" long tail in p.a. 280 deg was noted
(presumably for component A).
     The available astrometry for component B, the following orbital elements
by G. V. Williams, and an ephemeris appear on MPEC 2016-A36.

                    Epoch = 2016 Apr.  2.0 TT
     T = 2016 Mar. 17.2845 TT         Peri. = 152.4590
     e = 0.490400                     Node  =   3.7833  2000.0
     q = 1.573014 AU                  Incl. =   9.3873
       a =  3.086762 AU    n = 0.1817395    P =   5.42 years


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

                         (C) Copyright 2016 CBAT
2016 January 5                   (CBET 4231)              Daniel W. E. Green