Circular No. 6587 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) R. West, European Southern Observatory; and M. Kidger, Instituto de Astrofisica de Canarias, report on behalf of the European Comet Hale-Bopp Team: "High-resolution observations taken with the 1-m Jacobus Kapteyn Telescope of the Observatorio del Roque de los Muchachos by J. Licandro (Instituto de Astrofisica de Canarias) and P. Rudd (Royal Greenwich Observatory) on Mar. 6.2 UT broadly confirm the observations of Birkle and Boehnhardt reported on IAUC 6583. Observations were taken through a CN and a blue continuum filter, with Laplacian filtering applied to the reduced images. The images reveal both spiral-jet and arc structures. The spiral jet is seen in both filters and leaves the nucleus at p.a. about 200 deg, turning through a right angle at about 3" from the nucleus and continuing in p.a. 110 deg. A bright shell is also seen in both filters 20" to the southwest of the nucleus, which corresponds to a recently separated jet. Two diffuse arc structures are also seen to the north and east of the nucleus. The northern arc is only seen in the CN images, centered at 18" from the nucleus, and it extends from p.a. 90 deg to 270 deg through the north, being clearly elliptical, with the major axis in p.a. 340 deg. A second and fainter arc can be seen only in the continuum- subtracted CN image and extends from p.a. 30 deg to 120 deg, centered about 27" from the nucleus. The CN and continuum images can be found at http://www.iac.es/comet/ima97/mar5ifin.jpg. Assuming, as on IAUC 6583, that the two arcs are ejected by the same active spot and that the nucleus rotates with an 11.47-hr period (Lecacheaux et al., IAUC 6560; Jorda et al., IAUC 6583), we obtain an expansion velocity for CN of 1.3 km/s for a 60-deg rotation between arc emissions, very close to the velocity calculated by Birkle and Boehnhardt." J. E. Wink, Institut de Radio Astronomie Millimetrique (IRAM), Grenoble, reports on behalf of the continuum and molecular-lines observing teams (headed by W. J. Altenhoff, Max Planck Institut fur Radioastronomie; and D. Bockelee-Morvan, Observatoire de Paris, respectively): "We have detected the millimeter-wave continuum of C/1995 O1 with the IRAM Plateau de Bure Interferometer at 3 mm (resolution 3".5) and at 1 mm (resolution 1".5) on Mar. 9 and 11. On Mar. 11.4 UT, the flux density of the unresolved nucleus was 24 +/- 1 mJy at 229 GHz. This flux can be accounted for by thermal radiation at blackbody temperature 380 K from a 1600-km^2 area, which corresponds to a sphere of diameter 45 km. These observations were made simultaneously with molecular-line observations, which detected cometary emissions centered at the continuum position." (C) Copyright 1997 CBAT 1997 March 14 (6587) Daniel W. E. Green ================== RFC 822 Headers ================== Received: from mars.harvard.edu (mars.harvard.edu [131.142.10.32]) by cfa.harvard.edu (8.8.5/8.7.3) with SMTP id LAA22240; Fri, 14 Mar 1997 11:54:45 -0500 (EST) Received: from cfa0.harvard.edu by mars.harvard.edu (SMI-8.6/SMI-SVR4) id LAA17275; Fri, 14 Mar 1997 11:43:34 -0500 Received: by cfa0.harvard.edu (SMI-8.6/SMI-SVR4) id LAA24459; Fri, 14 Mar 1997 11:43:35 -0500 Date: Fri, 14 Mar 1997 11:43:35 -0500 From: dgreen@cfa0.harvard.edu (Daniel W. E. Green) Message-Id: <199703141643.LAA24459@cfa0.harvard.edu> To: quai@mars.harvard.edu Subject: IAUC 6587: C/1995 O1