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IAUC 9237: 253P; 45P

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IAUC number 

                                                  Circular No. 9237
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@EPS.HARVARD.EDU           ISSN 0081-0304
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET 253P/2011 R2 (PANSTARRS) = 1998 RS_22
     Further to IAUC 9231, Syuichi Nakano (Sumoto, Japan) has
identified this comet with observations made by the LINEAR survey
on 1998 Sept. 14 and 18 (and designated 1998 RS_22) and by the
Spacewatch survey on 2005 Dec. 1; these observations have been
published on MPEC 2011-U02.  Nakano notes that the correction for
the 1998 astrometry from the starting 2011 orbital elements is
Delta(T) = -2.29 days.  The permanent designation 253P is being
assigned to this comet.  The following revised orbital elements
linking the three apparitions are by Nakano; the time of perihelion
in 1998 was Dec. 14.0208 TT (epoch 1998 Dec. 13.0 TT).

                    Epoch = 2011 Nov. 15.0 TT
     T = 2011 Nov. 24.1115 TT         Peri. = 230.9982
     e = 0.412738                     Node  = 146.9357  2000.0
     q = 2.039461 AU                  Incl. =   4.9389
       a =  3.472830 AU    n = 0.1522926    P =   6.472 years


COMET 45P/HONDA-MRKOS-PAJDUSAKOVA
     I. M. Coulson, Joint Astronomy Centre, Hilo, Hawaii; Anthony
Remijan, National Radio Astronomy Observatory (NRAO); Stefanie
Milam, Geronimo Villanueva, Steven Charnley, Michael DiSanti, and
M. Mumma, Goddard Space Flight Center, NASA; and Yi-Jehng Kuan,
National Taiwan Normal University, report that observations of the
J=4-3 transition of HCN at 354.5055 GHz were made of comet 45P on
Aug. 19.75-19.98 UT with the James Clerk Maxwell Telescope on Mauna
Kea, and of the F=2-2 hyperfine transition of the J=3/2 level of OH
near 1667.359 MHz at the NRAO Green Bank telescope during Aug.
19.54-19.82.  At this time, the comet was 0.95 AU from the sun and
0.088 AU from the earth.  Four hours of integration revealed an HCN
line of peak brightness 0.018 K, a width (fitted, gaussian 1-sigma)
of 1200 m/s, and an integrated strength of 47 K m/s (S/N = 6.7).
Assuming isotropic outgassing, a gas temperature of 50 K, and
adopting an expansion velocity of 600 m/s yields Q(HCN)= 2.5 x
10**23 molecules/s.  The OH fitted-line parameters yield a peak
brightness of 0.0226 K, or a flux density of 0.0113 Jy, a linewidth
of 1890 m/s, and an integrated intensity about 20.358 mJy km/s for
a 3-sigma detection in 6.75 hours.  Following Tacconi-Garman et al.
(1990, Ap.J. 364, 672) and Schleicher and A'Hearn (1988, Ap.J. 331,
1058), the production rate of OH is Q(OH) about 1.4 x 10**26
molecules/s.

                      (C) Copyright 2011 CBAT
2011 November 9                (9237)            Daniel W. E. Green

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