[IAUC] IAUC 9183: 103P; 238P; C/2010 V1 [25139-2011/04-R1]

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                                                  Circular No. 9183
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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COMET 103P/HARTLEY
     H. Weaver, Applied Physics Laboratory (APL), Johns Hopkins
University (JHU); P. Feldman, JHU; M. A'Hearn, University of
Maryland; N. Dello Russo, APL/JHU; and A. Stern, Southwest Research
Institute, report the detection of several bands of CO fourth-
positive-group emission from comet 103P during Hubble Space
Telescope (HST) COS ultraviolet spectroscopic observations on Nov.
4.2 and 4.8 UT, which bracket the EPOXI spacecraft's closest
approach time of Nov. 4.583.  The CO emissions at the two different
times are identical to within about 15 percent.  Preliminary analysis
gives Q(CO) = 2-3 x 10**25 s**-1, assuming that CO is flowing
radially outward from the nucleus with a speed of 0.75 km/s.  If
Q(H_2O) is 1.0 x 10**28 s**-1, then CO/H_2O is 0.2-0.3 percent, which
is the smallest CO abundance ever measured in a comet.  Several
atomic emissions from S and C were also detected.  Analysis of wide-
band visible images also taken via the HST on Nov. 4.568 UT show a
dust jet emanating from the nucleus in the sunward direction at a
celestial position angle of 104 deg.


COMET 238P/READ
     H. H. Hsieh, University of Hawaii, reports that observations
of comet 238P/Read on Oct. 5 UT, using the 10-m Keck I telescope on
Mauna Kea, show that the comet has once again become active after
last being observed to be active in December 2005.  In a composite
image comprising 1140 s of effective exposure time, the comet
exhibits a short, tapered tail approximately 5" in length pointed
in the anti-solar direction (about 75 deg east of north) and a
small amount of coma (comet FWHM = 0".90, measured perpendicular to
the tail, compared to typical stellar FWHMs of 0".85).  The total
R-band magnitude (measured inside a 2".0 aperture) was 22.25 +/-
0.05.  This comet is notable for being the second main-belt comet
(MBC; Hsieh and Jewitt 2006, Science 312, 561) to have been
discovered, after 133P/Elst-Pizarro.  It is now also the second MBC
after 133P to be confirmed to have recurrent activity, a key
indication that sublimation, perhaps modulated by seasonal effects,
of volatile ice (and not a one-time event such as an impact) is
responsible for the observed activity.


COMET C/2010 V1 (IKEYA-MURAKAMI)
     Further to IAUCs 9175 and 9176, S. Nakano relates that K.
Ikeya was visually hunting for comets also on Nov. 1.8 UT, but
nothing was visible at the comet's position then to visual mag 9-10,
despite the fact that his sky conditions were better on Nov. 1.8
than on Nov. 2.8.

                      (C) Copyright 2010 CBAT
2010 November 6                (9183)            Daniel W. E. Green