Central Bureau for Astronomical Telegrams
IAUC 6240: C/1995 O1
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Circular No. 6240
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/1995 O1 (HALE-BOPP)
Z. Sekanina, Jet Propulsion Laboratory, writes: "The general
scenario for the bright jet's evolution (IAUC 6223) remains
plausible, with the sequence of high-resolution images taken
between mid-August and early September (and now available on the
World Wide Web) allowing one better to constrain the ejection times
and particle velocities. The spin period is still indeterminate
and is assumed to be 8 days. The best fit to the jet evolution is
then achieved if the ejection from the equatorial source lasted
from Aug. 17 through 19 (a quarter of the period) with velocities
between 30 and 50 m/s. The position of the rotation axis is
slightly revised to R.A. = 40 deg, Decl. = 0 deg (obliquity 150
deg). One may have to introduce a second source to simulate the
innermost part of the jet at p.a. 290 deg. The activity of this
source, at a moderate (but poorly defined) 'southern' latitude,
appears to have been of a very short duration, some time on Aug.
22, with ejection velocities of generally < 40 m/s."
M. Kidger, Instituto di Astrofisica de Canarias, reports that
this comet has been observed virtually every night in September
with the 0.82-m IAC-80 Telescope at Teide Observatory (sequences of
300-s exposures in R): "The latest images show the development of
a new and extremely bright jet. Since the decay of the spiral jet
observed up to Sept. 6, the nuclear condensation had been perfectly
circular, with no evidence of any important jet activity (through
Sept. 25.88 UT). However, on Sept. 26.88, an elongation of the
nuclear condensation was oriented east-west. By Sept. 27.88, this
elongation had rotated anticlockwise by about 45 deg (to p.a. 35
deg) and developed considerably into a jet similar to that observed
in late August. On Sept. 28, a long bright 'spiral' arm extends
clockwise from p.a. 323 deg (where the jet is straight) to 46 deg;
the distance from the nucleus to the point in the jet where it
starts to sweep in a clockwise direction is 4".5 on both Sept. 27
and 28. From this motion, we estimate a rotation period of about
4.9 days. The new images may be viewed on the World Wide Web at
URL http://www.ll.iac.es/general/index.html."
R. H. McNaught, Anglo-Australian Observatory, writes: "Images
with the 1.0-m reflector on Sept. 29 UT show the comet to have a
near-stellar nucleus with a high-intensity 3" jet in p.a. 320 deg.
The jet was only slightly fainter than the nucleus, which seems to
lie on the southern tip of the inner coma/tail, the jet comprising
the southwest boundary of the coma."
1995 September 29 (6240) Daniel W. E. Green
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