Electronic Telegram No. 1289
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
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COMET 17P/HOLMES
     M. Drahus and L. Paganini, Max-Planck-Institut fuer Sonnensystemforschung;
and L. Ziurys and W. Peters, Arizona Radio Observatory (ARO), communicate
their further monitoring of comet 17P at millimeter wavelengths (cf. IAUCs
8891, 8914) with the ARO 10-m Heinrich-Hertz Submillimeter Telescope on Mount
Graham.  Late evolution of the outburst was traced through the HCN(3-2)
transition.  The following integral sums of the antenna temperature were
obtained, given in units of K km/s:  2007 Nov. 29.20-29.24 UT, 0.08 +/- 0.05;
Dec. 5.13-5.36, 0.03 +/- 0.01; Dec. 28.13-28.31, < 0.06 (3-sigma upper limit).
Note that these values were not corrected for the main-beam efficiency.  The
profiles of the spectral line suggest lower gas-expansion velocity than in
October (cf. IAUC 8914), probably about 0.5 km/s.  Under several assumptions,
the following production rates were calculated, given as log Q(HCN):
2007 Nov. 29.20-29.24, 25.4; Dec. 5.13-5.36, 25.0; Dec. 28.13-28.31, < 25.4.
The half-power radius of the beam was 14.5 arcsec.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2008 CBAT
2008 March 6                     (CBET 1289)              Daniel W. E. Green