Central Bureau for Astronomical Telegrams
IAUC 6476: C/1996 Q1; C/1996 B2
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Circular No. 6476
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
COMET C/1996 Q1 (TABUR)
R. Schulz, Max-Planck-Institut fur Aeronomie; and G. P. Tozzi,
Osservatorio Astrofisico di Arcetri, report on observations of this
comet with the MPI/ESO 2.2-m telescope at the European Southern
Observatory on Sept. 12 and 13: "We found the comet quite peculiar
on Sept. 12, with a very high gas/dust ratio. On a low-resolution
spectrogram, the cometary emission lines were very intense and
there was almost no continuum. Moreover, narrowband CN images
indicate strong jet-like features in the coma. Spectra and images
taken on Sept. 13 indicate that the dust emission was much greater
than on the previous day; by measuring the relative intensity of C2
and the adjacent continuum, we found that the gas/dust ratio had
decreased by a factor of three in one day, and the overall
intensity increased by a factor of about two."
Visual m1 estimates (B = binoculars): Sept. 7.99 UT, 7.9 (A.
Baransky, Kiev, Ukraine, 0.11-m reflector); 10.39, 7.8 (R. Keen, Mt.
Thorodin, CO, 7x50 B); 15.82, 6.8 (J. Kobayashi, Kumamoto, Japan,
7x50 B); 18.11, 6.3 (R. J. Bouma, Groningen, The Netherlands, 15x80
B; tail 0.9 deg long in p.a. 279 deg); 20.11, 6.3 (K. Hornoch,
Lelekovice, Czech Republic, 10x80 B).
COMET C/1996 B2 (HYAKUTAKE)
C. B. Cosmovici, Institute for Space Physics, CNR, Frascati;
S. Montebugnoli and A. Orfei, Institute for Radioastronomy, CNR,
Medicina; S. Pogrebenko, JIVE, Dwingeloo; and S. Cortiglioni, TESRE,
CNR, Bologna, report: "We detected the 22-GHz water-emission line
from C/1996 B2 near the time of perihelion, using the 32-m dish of
the Medicina Radiotelescope and a programmable high-resolution
spectrum analyzer (9-MHz input bandwidth, 8192 channels) as back-
end; the field-of-view was 2'. The results are peculiar, with the
line being split into two clear and strong components (maximum
antenna temperature on May 3 was 130 +/- 20 mK), and positively
shifted from the zero-velocity point as follows: Apr. 26, 20 and
32 km/s; May 1, 27 and 35; 3, 34 and 41; 4, 38 and 45. A complete
analysis of the data exclude contamination by other possible
spectral lines and local oscillator position errors. As far as we
know, similar behavior of emission lines in comets has never before
been reported. In order to understand if this behavior is due to
jetting and/or bowshock physics, we encourage other observers to
communicate their ground- or space-based observations from the same
period to us at cosmo@ifsi.fra.cnr.it."
(C) Copyright 1996 CBAT
1996 September 20 (6476) Daniel W. E. Green
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