[IAUC] IAUC 9250: P/2010 UH_55 [25139-2012/04-R1]

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                                                  Circular No. 9250
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBATIAU en EPS.HARVARD.EDU           ISSN 0081-0304
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Prepared using the Tamkin Foundation Computer Network


COMET P/2010 UH_55 (SPACEWATCH)
     As first reported on CBET 2926, an apparently asteroidal
reported by the Spacewatch survey (discovery observations tabulated
below), and designated 2010 UH_55 by the Minor Planet Center in
late 2010, has been found to show cometary activity.  H. Sato
(Tokyo, Japan) first reported the appearance of a condensed coma of
size 6"-8" soon after discovery; his CCD images taken on 2010 Nov.
17.4 UT taken with a 0.50-m reflector suggest that the west side of
the object appeared soft, with a hint of tail 12" long.  Sato's
report of cometary appearance remained unconfirmed until a year
later, when he again found the object on 2011 Nov. 3.5 to be
moderately condensed a faint coma of diameter 40" (and mag 18.8
within a circular aperture of radius 19".7) with a 55" tail in
p.a. 290 deg with a f/4.5 reflector.  L. Buzzi (Varese, Italy;
0.38-m relector) found a compact coma 8" wide that was faintly
elongated out to 10"-15" in p.a. around 290 deg on stacked images
obtained on 2011 Nov. 15.15-15.17 in good seeing but with moonlight
interference.  D. Chestnov and A. Novichonok report that
unfiltered CCD images taken on Nov. 25.09 by V. Gerke with a 0.40-m
telescope showed that 2010 UH_55 has a small coma of total mag 18.7
and a 0'.2 tail in p.a. around 295 deg; stacked images taken on
Nov. 28.03 show the same morphology except with the tail in p.a.
319 deg.  G. Sostero, K. Rochowicz, N. Howes, and E. Guido write
that stacked R-band images taken remotely with the 2.0-m "Faulkes
Telescope North" at Haleakala on Nov. 28.6 show a diffuse coma
around 9" in diameter (mag 18.2-18.3) with a faint, broad tail
nearly 20" long toward the west-northwest.

     2010 UT             R.A. (2000) Decl.       Mag.   Observer
     Oct. 29.21706    3 31 53.06   +20 24 43.4   19.4   Spacewatch
          29.23481    3 31 52.58   +20 24 38.8   19.6     "
          29.25255    3 31 52.08   +20 24 34.7   19.7     "

S. Nakano notes that 2010 UH_55 passed 0.58 AU from Jupiter on 1946
June 5 and 0.42 AU from Saturn on 1900 Jan. 1 UT.  Revised orbital
elements by G. V. Williams from MPEC 2011-W82:

                    Epoch = 2011 Aug. 27.0 TT
     T = 2011 May  10.39701 TT        Peri. = 221.62832
     e = 0.5752275                    Node  = 235.26362 2000.0
     q = 2.7680070 AU                 Incl. =   8.66233
       a =  6.5164457 AU   n = 0.05924994   P =  16.6 years

                      (C) Copyright 2012 CBAT
2012 February 29               (9250)            Daniel W. E. Green