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IAUC 8355: C/2002 T7; C/2004 H6

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                                                  Circular No. 8355
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://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


COMET C/2002 T7 (LINEAR)
     M. L. Sitko, University of Cincinnati; R. W. Russell and D. L.
Kim, Aerospace Corporation; and S. M. Brafford, University of
Dayton, report 3-13-micron spectrophotometry of comet C/2002 T7,
obtained on May 31.1 UT with the 1.5-m University of Minnesota
telescope (+ Aerospace Broadband Array Spectrograph System; 8".5
aperture; 49" chop throw; integration times 10 min on the comet and
20 min on the reference star, beta Gem) at Mt. Lemmon: "A virtually
featureless comet continuum was seen to rise from 3.5 to 13 microns,
with only a very weak possible silicate emission band superimposed.
A blackbody with a temperature of about 300 +/- 10 K was fit to the
underlying continuum flux at 5, 8.4, and 12 microns.  This grain
temperature is about 9 +/- 4 percent higher than that of an
equilibrium blackbody at the heliocentric distance of the comet.
The silicate-feature-to-continuum ratio, based on the underlying
continuum fit, was about 1.03 +/- 0.02.  With our aperture, the
comet has the following narrowband (about 0.25 micron) magnitudes
and combined random errors (due to calibration star and comet, as
well as variations due to the presence of real spectral structure):
[3.7 microns] = 7.63 +0.44/-0.31, [4.7 microns] = 5.58 +/- 0.09, [5
microns] = 4.79 +0.49/-0.33, [8 microns] = 1.43 +/- 0.16, [10.5
microns] = 0.06 +/- 0.32, and [12 microns] = -0.39 +/- 0.02 (the
stated errors are standard deviations of the mean)."


COMET C/2004 H6 (SWAN)
     Improved parabolic orbital elements from MPC 52169:

     T = 2004 May  12.680 TT          Peri. = 269.030
                                      Node  = 317.239   2000.0
     q = 0.77605 AU                   Incl. = 107.653

2004 TT     R. A. (2000) Decl.   Delta     r    Elong. Phase   Mag.
June 14     2 49.46   -13 25.6   1.156   0.991   53.8   55.8    7.8
     19     2 37.14   -13 22.0   1.079   1.050   60.1   57.0    7.8
     24     2 22.76   -13 16.4   0.998   1.112   67.0   57.3    7.8
     29     2 05.48   -13 08.9   0.916   1.176   74.8   56.5    7.8
July  4     1 44.24   -12 58.9   0.835   1.243   83.7   54.4    7.8

     Visual total-magnitude estimates:  May 27.80 UT, 7.2 (C. E.
Drescher, Warrill View, Qld., 25x100 binoculars); 29.35, 7.3 (A.
Amorim, Florianopolis, Brazil, 20x80 binoculars); June 14.37, 7.5
(Amorim).

                      (C) Copyright 2004 CBAT
2004 June 16                   (8355)            Daniel W. E. Green

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