Central Bureau for Astronomical Telegrams

IAUC 8905: 17P; V2467 Cyg

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                                                  Circular No. 8905
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
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COMET 17P/HOLMES
     M. R. Combi, University of Michigan: J. T. T. Maekinen,
Finnish Meteorological Institute; and J.-L. Bertaux, E. Quemerais,
and S. Ferron, Service d'Aeronomie, CNRS/UVSQ, report that the
Solar Wind Anisotropies (SWAN) camera on the Solar and Heliospheric
Observatory (SOHO) spacecraft, located at the earth-sun L_1
Lagrange point, makes daily full-sky images of hydrogen Lyman_alpha.
SWAN detected comet 17P/Holmes beginning with the rapid rise of
activity on Oct. 24 UT.  The Lyman_alpha coma was observed to
expand and brighten over the next few days, as water -- and
subsequently OH -- were photodissociated to produce hydrogen.  An
initial expansion velocity in the range between 17 and 20 km/s was
deduced from a preliminary analysis of the images, which is
consistent with the initial production of H atoms from the
photodissociation of water.  A preliminary time-series analysis of
the images (Maekinen and Combi 2005, Icarus 177, 217) yields daily
averages of the global water-production rate.  This indicates that
there was a rapid rise in the water-production rate by Oct. 25,
resembling the visual light curve, from a value of 1.2 x 10**(30)
molecules/s to a maximum of 1.4 x 10**(30) on Oct. 27.  This was
followed by a fairly steady decrease to a value of 7.8 x 10**(29) by
Nov. 16.
     Visual total-magnitude and coma-diameter estimates:  Nov.
16.87 UT, 2.8, 40' (K. Hornoch, Vohancice, Czech Republic, 1x50
monocular); 18.05, 3.0, 37' (A. Pereira, Cabo da Roca, Portugal,
5x22 monocular); 24.04, 3.0, 35' (B. H. Granslo, Fjellhamar, Norway,
6x30 monocular); 27.81, 2.9, 40' (J. J. Gonzalez, Leon, Spain, 4x30
opera glasses); Dec. 1.79, 3.0, 60' (M. Meyer, Limburg, Germany,
3.5x15 opera glasses); 6.60, 3.3, 50' (S. Yoshida, Kanagawa, Japan,
10x66 refractor); 8.78, 3.3, 50' (Gonzalez); 11.89, 3.1, about 60'
(Pereira); 15.83, 3.3, 60' (Meyer); 18.88, 3.3, 65' (Hornoch;
moonlight).


V2467 CYGNI
     R. B. Perry, Langley Research Center, NASA; R. J. Rudy, D. K.
Lynch, T. R. Prater, S. Mazuk, and A. M. Gilbert, The Aerospace
Corporation; and R. C. Puetter, University of California, San
Diego; report 0.47- to 2.5-micron spectroscopy of V2467 Cyg (cf.
IAUC 8821, 8888) on 2007 Dec. 14 UT using VNIRIS on the Lick 3-m
telescope.  The object remains bright and shows many high-
excitation emission lines.  Coronal lines of [SI VII], [Ca VIII],
[Si X], and [S XI] showed notched, doubled line profiles.  Also
present were lines of H I, He I, He II, weak O I, and the
unidentified novae lines.  There was no evidence of thermal
emission from dust.

                      (C) Copyright 2007 CBAT
2007 December 20               (8905)            Daniel W. E. Green

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