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IAUC 8571: 2005db; 9P

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                                                  Circular No. 8571
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     L. A. G. Monard, Pretoria, South Africa, reports his discovery
of an apparent supernova (mag about 17.3) on unfiltered CCD images
taken on July 19.144 UT (and confirmed on July 20.058 at mag about
17.4) with the 0.30-m Schmidt-Cassegrain reflector at the Bronberg
Observatory near Pretoria.  SN 2005db is located at R.A. =
0h41m26s.79, Decl. = +25o29'51".6 (equinox 2000.0), which is 16"
west and 2" south of the nucleus of NGC 214.  Nothing is visible at
this location on Monard's images taken on July 2.159 (limiting red
mag 18.5) or on the Digitized Sky Survey (limiting red mag 20.5).

     C. M. Lisse, Applied Physics Laboratory, Johns Hopkins
University, and University of Maryland; J. Van Cleve, Ball
Aerospace; Y. R. Fernandez and K. J. Meech, University of Hawaii;
and the Spitzer Deep Impact team report that the Spitzer Space
Telescope (SST) strongly detected the ejected material from comet
9P during a long-term monitoring campaign of the 'Deep Impact'
encounter.  The brightness of the comet's continuum after impact
(at 16 microns and within a 10"-wide aperture) shows a sharp,
doubly inflected rise to a total post-impact excess of 25 percent
over the course of 2 hr from the time of spacecraft impact at July
4.244 UT.  A 5-35-micron spectrum of the comet taken 36 min after
impact shows a flux density of about 1 Jy due to the ejecta, on top
of the ambient coma signal of about 4 Jy.  Silicate emission
features indicative of crystalline olivines and pyroxenes were seen
in the 9-37-micron region of the spectrum, superimposed on a 325-K
continuum.  The silicate emission bands in the range 8-13 microns
were about 500 percent of the continuum.  From the relative line
strengths of the bands, amorphous silicates must be present, as
well.  The spectral signature of polyaromatic hydrocarbons (PAHs)
at 6.8, 7.7, and 11.3 microns is small compared to the silicate
emission, but detectable.  Spectral features due to water ice,
water vapor, and carbonaceous materials (carbonates and
hydrogenated aromatic hydrocarbons) were detected in the 5.8-7.2-
micron region.  Emission features attributed to carbon dioxide were
found at 13.4, 13.9, 15.1, and 15.3 microns.  New cometary features
at 12.5, 28, and 31.5 microns are tentatively assigned to
crystalline aluminum oxide.  The ejecta spectral signatures were
detected from the time of impact through at least 41 hr afterwards,
but by 121 hr after impact all spectral signatures above the pre-
impact levels were absent.  The SST will continue to observe the
comet periodically through Aug. 16.

                      (C) Copyright 2005 CBAT
2005 July 22                   (8571)            Daniel W. E. Green

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