Electronic Telegram No. 4151
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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Prepared using the Tamkin Foundation Computer Network


COMET P/2015 TO_19 (LEMMON-PANSTARRS)
     R. Wainscoat and R. Weryk reported the discovery of a possible comet in
four w-band exposures taken with the 1.8-m Pan-STARRS1 telescope at Haleakala
on Oct. 13 UT (discovery observations tabulated immediately below), noting
that the object appears extended relative to the adjacent stars in each image
in the sequence, but that the evidence for cometary activity is subtle.

     2015 UT             R.A. (2000) Decl.       Mag.
     Oct. 13.35475    0 52 30.13   +14 22 22.1   20.4
          13.34361    0 52 30.60   +14 22 24.0   20.4
          13.33251    0 52 31.06   +14 22 25.8   20.4
          13.31890    0 52 31.62   +14 22 28.2   20.4

G. V. Williams then found earlier astrometry in the Minor Planet Center
database of the apparently asteroidal object, first from single nights at
Catalina on Oct. 8 and at Haleakala on Oct. 12, and then linking those to an
object found via the Mount Lemmon Survey on Oct. 3 and 4 (observer D. C.
Fuls; astrometry provided below) with the new minor-planet designation 2015
TO_19 (cf. MPS 628842); Williams also then identified Pan-STARRS1 astrometry
of this object acquired on Sept. 12.

     2015 UT             R.A. (2000) Decl.       Mag.   Observer
     Oct.  3.26021    0 59 13.23   +14 47 29.6          Fuls
           3.26620    0 59 12.97   +14 47 28.7            "
           3.27130    0 59 12.75   +14 47 28.5   20.6     "
           3.27641    0 59 12.55   +14 47 27.5   20.4     "
           4.31597    0 58 31.75   +14 45 18.0   20.5     "
           4.32203    0 58 31.50   +14 45 17.0   20.4     "
           4.32809    0 58 31.23   +14 45 16.1   20.3     "
           4.33415    0 58 30.99   +14 45 15.0   20.4     "

As a result of the Pan-STARRS1 Oct. 13 observations, M. Micheli, R. Wainscoat,
and R. Weryk obtained three follow-up 60-s exposures of 2015 TO_19 at the
Canada-France-Hawaii Telescope on Oct. 14.3 UT (queue observer C. Wipper),
which show that the object has a diffuse appearance and displays a clear 8"
tail in p.a. of about 220 deg.  After the object was posted on the MPC's
NEOCP webpage, H. Sato (Tokyo, Japan) acquired nine stacked 60-s exposures
on Oct. 14.5 with a 0.51-m f/6.8 astrograph at Siding Spring, which show the
comet to be strongly condensed with an 8" coma, no tail, and a w-band
magnitude of 19.3 as measured within a circular aperture of radius 6".6.
     The available astrometry, the following elliptical orbital elements by
Williams, and an ephemeris appear on MPEC 2015-T117.

                    Epoch = 2016 Feb. 22.0 TT
     T = 2016 Mar.  7.8325 TT         Peri. =  89.4556
     e = 0.359190                     Node  = 321.6660  2000.0
     q = 2.925106 AU                  Incl. =   6.5025
       a =  4.564701 AU    n = 0.1010615    P =   9.75 years


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

                         (C) Copyright 2015 CBAT
2015 October 15                  (CBET 4151)              Daniel W. E. Green