Electronic Telegram No. 2509
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET 238P/READ
     H. H. Hsieh, University of Hawaii, reports that observations of 238P/Read
on October 5 UT using the 10-m Keck I telescope on Mauna Kea show that
it 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.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2010 CBAT
2010 October 19                  (CBET 2509)              Michael Rudenko