[IAUC] IAUC 9223: P/2011 P1; C/2010 X1 [25139-2012/04-R1]

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                                                  Circular No. 9223
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
New postal address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBATIAU en EPS.HARVARD.EDU           ISSN 0081-0304
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET P/2011 P1 (McNAUGHT)
     As first announced on CBET 2779, R. H. McNaught reports his
discovery of a comet (discovery observation tabulated below;
replaces that on CBET 2779) on CCD images taken with the 0.5-m
Uppsala Schmidt telescope at Siding Spring; the discovery images
show the comet to be diffuse with a circular coma of diameter about
20"; four stacked images later show a condensation and extension to
the north and south.  Eight stacked 60-s exposures by McNaught on
Aug. 2.7 UT show a similar-sized coma spanning p.a. 30-210 deg with
an apparent tail toward the west.  Ten stacked 60-s images taken on
Aug. 3.7 show the eastern edge of the coma to be much brighter
extending 10" in p.a. 10 deg and 13" in p.a. 215 deg, like a tail
and an anti-tail (but from previous images, this appears to be the
eastern edge of the coma).  Following posting on the Minor Planet
Center's NEOCP webpage, other CCD astrometrists also have commented
on the object's cometary appearance (cf. CBET 2779).

     2011 UT             R.A. (2000) Decl.       Mag.   Observer
     Aug.  1.77495    2 30 48.48   +17 06 47.2   18.6   McNaught

The early astrometry appears on MPC 75580-75581; the following
orbital elements by G. V. Williams are from 49 observations (Aug.
1-29):

                    Epoch = 2011 Aug. 27.0 TT
     T = 2010 July  5.3310 TT         Peri. = 339.2843
     e = 0.413561                     Node  =   9.9815  2000.0
     q = 4.885067 AU                  Incl. =   6.2747
       a =  8.330046 AU    n = 0.0409952    P =  24.04 years


COMET C/2010 X1 (ELENIN)
     M. Drahus, University of California at Los Angeles; Bin Yang,
University of Hawaii; and J. Hoge, Joint Astronomy Centre, report
the detection of HCN in comet C/2010 X1 on July 30 when at
heliocentric distance r = 1.07 AU.  Observations between July
30.153 and 30.249 UT at the James Clerk Maxwell Telescope show the
J = 4-3 line with area about 0.1 K km/s in antenna temperature
scale.  Assuming an isotropic production of gas at velocity 0.5
km/s and a Boltzmann distribution of energy levels at 50 K, the
derived HCN production rate is 1.5 x 10^{25 molecules/s, comparable
to the mean level measured in comet 103P/Hartley at the same
heliocentric distance in late 2010 (Drahus et al. 2011, Ap.J. 734,
L4).

                      (C) Copyright 2011 CBAT
2011 September 11              (9223)            Daniel W. E. Green