[IAUC] CBET 4246: 20160129 : COMET C/2015 VL62 = 2015 YY6

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                                                  Electronic Telegram No. 4246
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/2015 VL62 = 2015 YY6
     On Jan. 23, E. Lilly and R. Weryk, Institute for Astronomy, University
of Hawaii, reported the discovery of a comet of an apparent comet in four
i-band exposures taken on Jan. 23.3 UT with the 1.8-m Pan-STARRS1 telescope
on Haleakala (discovery observations tabulated below); the object was
marginally cometary in appearance, with FHWM = 1".3 (vs. 1".0 for adjacent
stars), but there was evidence of a faint tail, extending towards the east
for approximately 3".

     2016 UT             R.A. (2000) Decl.       Mag.
     Jan. 23.29589    3 20 20.56   +26 50 15.5   19.8
          23.30534    3 20 20.21   +26 50 13.8   19.9
          23.31480    3 20 19.86   +26 50 12.4   19.5
          23.32433    3 20 19.51   +26 50 10.8   19.7

The object was posted on the Minor Planet Center's PCCP webpage.  Weryk
subsequently reported that he identified observations of this object in three
w-band Pan-STARRS1 images acquired on 2015 Dec. 16.3 UT, the object then
appeared asymmetric, with a small extension < 2" long towards the east, with
the comet's head having FWHM about 1".6 (vs. 1".2 seeing); the magnitude was
measured to be 19.8-19.9.  Weryk then also suggested identity of this object
with 2015 YY6, an apparently asteroidal object of red mag 19.0-19.5 reported
by W. K. Y. Yeung and observed on 2015 Dec. 18 and 19 with a 0.7-m f/3
reflector near Mayhill, NM, USA (and published with that designation on MPS
662873).  G. V. Williams confirmed these identifications and then found also
an identification with an object detected in 2015 November at Mount Lemmon
in observations made by R. G. Matheny (Nov. 2) and by E. J. Christensen (Nov.
3), at which time those observations had been given the minor-planet
designation 2015 VL62 on MPS 645811.  These observations are tabulated
below:

     2015 UT             R.A. (2000) Decl.       Mag.   Observer
     Nov.  2.49797    4 39 22.74   +29 45 27.5   20.7   Matheny
           2.50207    4 39 22.55   +29 45 27.4   20.2     "
           2.50617    4 39 22.30   +29 45 27.3   20.7     "
           2.51027    4 39 22.09   +29 45 27.1   20.3     "
           3.42074    4 38 32.46   +29 45 24.2   20.4   Christensen
           3.42766    4 38 32.09   +29 45 24.2   20.1     "
           3.43459    4 38 31.69   +29 45 23.9   20.5     "
           3.44151    4 38 31.31   +29 45 23.9   20.3     "
     Dec. 18.13517    3 51 12.64   +28 38 36.0   19.1   Yeung
          18.25109    3 51 05.33   +28 38 18.0   19.3     "
          19.12080    3 50 10.66   +28 35 52.4   19.5     "
          19.23661    3 50 03.29   +28 35 33.3   19.0     "

Observations of 2015 VL62 were also reported via the Catalina Sky Survey on
2015 Nov. 8.4 UT (at mag 19.9-20.2) and Dec. 8.2 (when it had brightened to
mag 19.2-19.7); these were identified by Williams after the link was made
between the Nov. 2-3 and Dec. 18-19 observations.
     After the object was posted on the PCCP webpage, other CCD astrometrists
have also commented on the objects cometary appearance.  H. Sato, Tokyo,
Japan, writes that twelve stacked 60-s exposures taken on Jan. 29.1 with an
iTelescope 0.43-m f/6.8 astrograph (+ luminance filter) near Mayhill, NM,
USA, show the object to be strongly condensed with a coma 8" in diameter and
a hint of tail 15" long toward p.a. 270 degrees; the w-band magnitude was
18.8 as measured within a circular aperture of radius 5".7.  V-band images
taken by W. H. Ryan and E. V. Ryan with the Magdalena Ridge Observatory 2.4-m
f/8.9 reflector on Jan. 29.1 show a short, distinct tail at p.a. about 80
deg; the magnitude was measured to be 19.9-20.0.
     The available astrometry (spanning 2015 Nov. 2-2016 Jan. 29), the
following hyperbolic orbital elements by G. V. Williams, and an ephemeris
appear on MPEC 2016-B85.

                    Epoch = 2017 Sept. 4.0 TT
     T = 2017 Aug. 28.74212 TT        Peri. = 128.32371
     e = 1.0018347                    Node  =  94.55854 2000.0
     q = 2.7232191 AU                 Incl. = 165.61705


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

                         (C) Copyright 2016 CBAT
2016 January 29                  (CBET 4246)              Daniel W. E. Green