Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 6590: C/1995 O1

The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).


Read IAUC 6589  SEARCH Read IAUC 6591

View IAUC 6590 in .dvi or .ps format.
IAUC number


                                                 Circular No. 6590
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)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


COMET C/1995 O1 (HALE-BOPP)
     C. M. Wright, Max-Planck-Institut fur Extraterrestrische
Physik (MPE); C. H. Smith, University College, Australian Defence
Force Academy; A. Krabbe, MPE; T. Lehmann, University of Jena; and
T. Boeker, Space Telescope Science Institute, report:  "Images in a
broad-band 8-13-micron filter (N band) with the MPG/ESO 2.2-m
telescope (+ mid-infrared camera MANIAC) on 1996 Oct. 28.8, 30.8,
31.8, and Nov. 1.8 UT show a clear fan-shaped structure extending
about 30" in length, with a symmetry axis pointing almost due east.
The size and orientation appeared stable over all four nights, and
there was no obvious jet activity.  N-band fluxes in a 21".6-
diameter aperture were 14.7 +/- 0.3, 16.7 +/- 0.1, 18.4 +/- 0.1,
and 18.0 +/-  0.1 x 10E-17 W cmE-2 micronE-1, respectively, on the
four nights.  Images in a broad-band 17.3-22.7-micron filter (Q
band) on Oct. 30.8 and 31.8 and Nov. 1.8 showed a morphology
consistent with that in the N band; Q-band fluxes (21".6 aperture)
were 16.0 +/- 0.2, 12.6 +/- 0.3, and 14.8 +/- 0.4 x 10E-17 W cmE-2
micronE-1.  (Uncertainties are statistical; absolute calibration is
about 30 percent).  N-to-Q color temperatures (with no correction
for silicate emission) on Oct. 30.8, 31.8, and Nov. 1.8 were 207,
233, and 218 +/- 15 K, respectively.  We see little evidence for
variability.  On Nov. 1.8, fluxes in a 21".6-diameter aperture in
narrow-band 8.025-, 10.53-, and 12.95-micron filters were 2.1 +/-
0.5, 11.1 +/- 0.4, and 7.2 +/- 0.3 x 10E-17 W cmE-2 micronE-1,
respectively.  The 8.0-13.0-micron color temperature is 188 +/- 12
K, only marginally above the 175 K expected from a blackbody in
radiative equilibrium at 2.5 AU from the sun.  The silicate feature,
as judged from the 10.5-micron data, is a factor of 2.1 +/- 0.2
above the 188 K continuum."
     A. Lovell, P. Schloerb, C. DeVries, J. Dickens, W. Irvine, and
M. Senay, University of Massachusetts, write:  "Maps (field size 4'
x 4'; resolution 1') obtained during Mar. 11-13 with the FCRAO 14-m
antenna (+ focal-plane array receiver) of the HCN J=1-0, CS J=2-1,
and HCO+ J=1-0 transitions show that HCN and CS emission peaks at
the position of the nucleus, but the HCO+ emission is highly
asymmetric (peaking at a point offset 1'.5 from the nucleus in p.a.
about 320 deg; anti-sunward direction was about p.a. 340 deg).
There is a small HCN extension toward the p.a. of peak HCO+
brightness.  The HCN and CS lines have widths of 2.0 km/s and are
centered on the velocity of the nucleus.  However, the HCO+ line is
broader at the nucleus position (width 3.2 km/s), and it is
redshifted by 1.0 km/s.  The HCO+ line width increases to 4.1 km/s
at its peak-intensity position, and there is a small increase in
the observed redshift of about 0.2 km/s."

                      (C) Copyright 1997 CBAT
1997 March 17                  (6590)            Daniel W. E. Green

Read IAUC 6589  SEARCH Read IAUC 6591

View IAUC 6590 in .dvi or .ps format.


Our Web policy. Index to the CBAT/MPC/ICQ pages.


Valid HTML 4.01!