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IAUC 6614: C/1995 O1

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                                                 Circular No. 6614
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)
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Phone 617-495-7244/7440/7444 (for emergency use only)


COMET C/1995 O1 (HALE-BOPP)
     D. Mehringer, Caltech Submillimeter Observatory (CSO); P.
Colom, Observatoire de Paris (OP); D. Benford, CSO; D. Bockelee-
Morvan, OP; D. Despois, Observatoire de Bordeaux; G. Paubert,
Institut de Radioastronomie Millimetrique (IRAM); B. Germain, N.
Biver, J. Crovisier, D. Gautier, E. Gerard, and H. Rauer, OP; D. C.
Lis and T. G. Phillips, CSO; R. Moreno, IRAM; and J. K. Davies and
W. R. F. Dent, Joint Astronomy Centre, Hilo, report the
identification of formamide (NH2CHO) in comet C/1995 O1: "On Apr. 5
UT, we detected the lines of NH2CHO at 254.877 and 227.606 GHz with
the CSO and IRAM 30-m telescopes, respectively.  The integrated
line areas in the main-beam brightness temperature scale are 0.070
+/- 0.009 (254.9 GHz) and 0.28 +/- 0.02 (227.6 GHz) K km/s.  The
line at 218.459 GHz was also marginally detected (0.26 +/- 0.06 K
km/s) with the IRAM 30-m telescope.  A preliminary estimate of the
NH2CHO production rate is 3 to 5 x 10E27 molecules/s.  The 252-GHz
lines of methanol observed with the CSO on Apr. 3 agree with a
rotational temperature of 119 +/- 9 K."
     A. Owens, T. Oosterbroek, A. Orr, and A. N. Parmar, Space
Science Department, European Space Agency; L. A. Antonelli and F.
Fiore, BeppoSAX Science Data Center, Rome; M. C. Maccarone,
Istituto di Fisica Cosmica e Applicazioni Informatica, CNR, Palermo;
and L. Piro, Insituto Astrofisica Spaziale, CNR, Frascati, on
behalf of the BeppoSAX team, report the detection of soft x-rays
from the direction of comet C/1995 O1 by the LECS instrument
onboard BeppoSAX:  "The observations took place between 1996 Sept.
10.16 and 11.18 UT.  After correcting for the comet's motion, a 10-
sigma enhancement was found within 3' of the expected location of
the nucleus at much greater than 99.99-percent confidence.  A weak,
2.7-sigma enhancement was also found in motion-corrected MECS data
at the same location.  The extracted LECS spectrum is well fit by a
thermal bremsstrahlung model of kT = 0.36 keV -- consistent with
that observed in other comets (e.g., Lisse et al. 1996, Science 274,
205).  The total 0.10-2.0-keV luminosity is 6 x 10E16 erg/s,
comparable with the observed luminosities of comets C/1996 B2 and
C/1990 N1.  There is no evidence for fluorescent carbon or oxygen
emission with 95-percent-confidence upper flux limits of 1 x 10E-4
photons cmE-2 sE-1 and 3 x 10E-4 photons cmE-2 sE-1 for narrow line
emission at 282 and 523 eV, respectively.  This imples that if
lines are present, their total luminosity must be < 10 percent of
the continuum luminosity."

                      (C) Copyright 1997 CBAT
1997 April 7                   (6614)            Daniel W. E. Green

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