[IAUC] CBET 3749: 20131212 : COMET P/2013 TL_117 = 2013 UT_2 (LEMMON)

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                                                  Electronic Telegram No. 3749
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET P/2013 TL_117 = 2013 UT_2 (LEMMON)
     An apparently asteroidal object discovered in the course of the Mount
Lemmon Survey on images taken with the 1.5-m reflector by J. A. Johnson (cf.
MPS 480569, where it was given the designation 2013 TL_117) has been found
now to show cometary activity by CCD observers elsewhere.  (The object was
also assigned the designation 2013 UT_2 by the Minor Planet Center on MPS
482596 when Johnson sent observations that he obtained at Catalina on Oct.
24.)

     2013 UT             R.A. (2000) Decl.       Mag.   Observer
     Oct.  4.25039    1 42 25.60   +16 23 06.1   20.1   Johnson
           4.25737    1 42 25.17   +16 23 07.1   20.1     "
           4.26441    1 42 24.76   +16 23 09.0   20.1     "
           4.27144    1 42 24.33   +16 23 10.3   20.1     "

R. Behrend, Geneva Observatory; and L. Buzzi, Varese, Italy, both reported
that stacked images taken on Dec. 1.84 UT with a 0.90-m f/6.7 reflector by
Jose de Queiroz at Falera, Switzerland, suggested that this object might be
showing slight cometary features; Buzzi noted it to appear then as slightly
diffuse (FWHM = 5".4, while nearby stars have FWHM = 4".3) with a possible
coma 12" wide.  Buzzi then obtained images of the object on Dec. 2.88 with a
0.60-m f/4.64 reflector at Varese that showed it to be slightly diffuse with a
possible coma up to 14" wide; follow-up observations by Buzzi and G. Galli
with better sky conditions on Dec. 7.72-7.79 show an asymmetric coma 14" x 11"
in size, possibly elongated to the east.  Inspection of stacked archival
images taken by R. Holmes with a 0.61-m f/4 reflector from Westfield, IL, USA,
in good seeing on Nov. 25.11 (measured by S. Foglia and Buzzi) also reveal a
softer aspect, with a coma around 10" wide.  Behrend adds that follow-up
images obtained by de Queiroz on Dec. 4.73-4.76 show the object to be more
diffuse then stars on each of the partial stacks, with no sign of a tail.
Carl W. Hergenrother, Lunar and Planetary Laboratory, writes that a co-added
720-sR-band image taken with a 1.8-m reflector at Mt. Graham on Dec. 12.08
shows a coma 15" diameter and tail of length 11" in p.a. 115 deg; he adds that
the comet showed no obvious coma or tail in a co-added 540-s R-band image
taken on Nov. 12.20, and that the object has brightened from mag 19.0-19.2 on
Nov. 12.2 to 18.5-18.6 on Dec. 7.1.  H. Sato (Tokyo, Japan; remotely using an
iTelescope 0.51-m f/6.8 astrograph at Siding Spring on Dec. 7.44-7.45) finds
an 8" disk-like center and 15" of outer coma with no obvious tail on eight
stacked 60-s images; the luminance-filter magnitude, as measured within a
circular aperture of radius 9".8, was 17.9.  William H. Ryan (Magdalena Ridge
Observatory, 2.4-m f/8.9 reflector; Dec. 12.1; reports that there is an
elongated coma toward p.a. about 90 deg in R-band images.
     The available astrometry, the following elliptical orbital elements by
G. V. Williams, and an orbit appear on MPEC 2013-X59.

                    Epoch = 2014 Mar.  4.0 TT
     T = 2014 Feb. 18.21879 TT        Peri. = 112.20037
     e = 0.6899431                    Node  =   3.36016 2000.0
     q = 1.1176706 AU                 Incl. =   9.36584
       a =  3.6047271 AU   n = 0.14401094   P =   6.84 years


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                         (C) Copyright 2013 CBAT
2013 December 12                 (CBET 3749)              Daniel W. E. Green