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IAUC 6607: C/1995 O1; 1991 VH

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                                                 Circular No. 6607
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
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     L. Woodney, University of Maryland (UM); J. McMullin, National
Radio Astronomy Observatory (NRAO); M. A'Hearn, UM; and N.
Samarasinha, National Optical Astronomy Observatory, write:  "In
observations at the NRAO 12-m telescope on Mar. 23 UT, we detected
H2CS for the first time in C/1995 O1.  The 7(16)-6(15) line at
244.0478 GHz had a peak (corrected main-beam brightness)
temperature of 0.02 K, and FWHM of 3 km/s.  Assuming a rotational
temperature of 80 K, we derive a production rate of 5.4 x 10E26.
OCS J(12-11) measured on Mar. 22 had a production rate of 6.1 x
10E27 mol/s."
     M. K. Bird and P. Janardhan, University of Bonn; and P.
Gemsheimer, W. Huchtmeier and T. L. Wilson, Max-Planck-Institut fur
Radioastronomie (MPIfR), Bonn, report detection of ammonia in comet
C/1995 O1 using the 100-m MPIfR radio telescope at Effelsberg.  The
following peak main-beam brightness temperatures were detected for
three individual K-band lines of NH3:  (3,3) at 23.870 GHz, 0.42 K;
(2,2) at 23.723 GHz, 0.26 K; (1,1) at 23.695 GHz, 0.13 K.  The
standard error for all three measurements is 0.04 K.   A main-beam
brightness temperature of 1 K is equivalent to a flux density of
0.7 Jy for observations at these frequencies.  The lines are
centered symmetrically on the velocity of the cometary nucleus.
The full width at half-maximum of the (3,3) line is 1.6 km/s.  No
noticeable changes in the strengths of the lines could be detected
between the two observation dates on Mar. 13.4 and 25.5.

1991 VH
     P. Pravec, M. Wolf, and L. Sarounova, Ondrejov Observatory,
report:  "Our photometric observations of this Apollo object on ten
nights during Feb. 27-Mar. 13 revealed the presence of two periods
in the lightcurve, 2.6236 +/- 0.0003 and 32.74 +/- 0.05 hr.
Analysis of the lightcurve suggests that, like 1994 AW1 (which has
a rather similar orbit), 1991 VH may be an eclipsing/occulting
binary (Pravec and Hahn 1997, Icarus, in press).  Further
observations of the eclipse/occultation events from more than one
station are desirable.  A current ephemeris for the object is on
MPC 27570.  Approximate ephemerides for the primary and secondary
minima are JD 2450518.38 + 1.364E and 2450520.37 + 1.364E,
respectively.  See http://sunkl.asu.cas.cz/~ppravec/91vh.html for

                      (C) Copyright 1997 CBAT
1997 March 29                  (6607)            Daniel W. E. Green

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