Central Bureau for Astronomical Telegrams
IAUC 8887: 17P
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Circular No. 8887
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)
CBAT@CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
COMET 17P/HOLMES
H. Kobayashi, H. Kawakita, and A. Nishikoji, Kyoto Sangyo
University, report that they have obtained low-dispersion spectra
of comet 17P on Oct. 24.58 and 25.46 UT with a 28-cm telescope (+
F2SPEC spectrograph; range 380-750 nm, resolution 900 at 600 nm).
The comet's spectrum on Oct. 24.58 was dominated by reflected
sunlight, and there were no significant emission bands and lines
visible. The Oct. 25.46 spectrum was still dominated by reflected
sunlight, but emission bands and lines (CN and C_2 bands, as well
as [O I] emission lines) appeared in the spectrum. The authors
speculate that this delay in the visibility of emission might be at
least partly caused by sublimation from icy grains ejected at the
outburst.
R. M. Wagner, LBT Observatory; S. Starrfield, Arizona State
University; G. Schwarz, West Chester University; S. Larson, Lunar
and Planetary Laboratory; and R. Kaitchuck, J. Childers, and G.
Turner, Ball State University, write that they obtained several
long-slit spectra (slit length 3'.7 in p.a. 90 deg; range 340-640
nm; resolution 0.6 nm) of comet 17P on Oct. 25.181 and 25.465 UT
with the Bok 2.3-m telescope on Kitt Peak. The spectra exhibit a
strong reflected continuum arising from dust. The spatial
continuum profile along the slit is strongly peaked in the inner
0'.5 but extends out to a diameter of about 1'.5; the profile also
appears asymmetric to the east and becomes more pronounced and
wider in the later spectrum, suggesting that dynamical effects
arising from the outburst are visible in the inner coma. Molecular
emission bands of CN, C_3, C_2, and NH_2 -- typical of other
gaseous comets -- are detected, as well, and are prominent away
from the bright optocenter. Emission from CN (0-0) can be traced
out to at least 2'.4 from the optocenter in each direction.
Further reductions and analyses are underway. Additional
spectroscopy to study the evolution of the dust and gas is
encouraged.
A. Fitzsimmons, Queen's University, Belfast; C. Snodgrass,
European Southern Observatory; and J. Southworth, University of
Warwick, report that spectra of comet 17P, centered on the central
condensation, were obtained on Oct. 26.05 UT using the 2.5-m Nordic
Optical Telescope (+ FIES echelle spectrograph; range 370-730 nm,
resolution 48000) on La Palma. The spectra are dominated by a
reflected solar spectrum from dust grains. Molecular emission bands
due to CN at 388 nm, C_3 at 405 nm, and C_2 at 516 nm are also
visible.
Further naked-eye magnitude estimates (cf. IAUC 8886): Oct.
25.29 UT, 2.8 (C. W. Hergenrother, Tucson, AZ, U.S.A.); 26.07, 2.6
(A. Pereira, Carnaxide, Portugal); 26.90, 2.4 (J. Carvajal, Madrid,
Spain).
(C) Copyright 2007 CBAT
2007 October 26 (8887) Daniel W. E. Green
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