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IAUC 7179: V382 Vel = N Vel 1999; 95P

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                                                  Circular No. 7179
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/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)


V382 VELORUM = NOVA VELORUM 1999
     Additional photometry by A. C. Gilmore with the 0.6-m f/16
reflector at Mount John University Observatory (cf. IAUC 7176; poor
conditions with cirrus clouds):  May 23.330 UT, V = 2.66(5), U-B =
+0.06(2), B-V = +0.54(2), V-R = +0.34(2), V-I = +0.56(2) (airmass
1.015); May 24.312, 3.28(3), -0.38(1), +0.37(2), +0.38(3), +0.89(4).
     Selected visual magnitude estimates:  May 22.8958 UT, 3.0 (R.
Levai, Sao Paulo, Brazil; independent discovery, forwarded by T. A.
Napoleao); 23.917, 2.9 (T. A. Napoleao, Sao Paulo, Brazil); 24.334,
3.0 (D. A. J. Seargent, The Entrance, N.S.W.); 24.569, 3.4 (A.
Pearce, Nedlands, W. Australia); 24.937, 3.2 (J. G. de S. Aguiar,
Campinas, Brazil); 25.23, 3.8 (S. J. O'Meara, Volcano, HI); 25.43,
3.8 (R. H. McNaught, Bugaldie, N.S.W.).


COMET 95P/CHIRON
     D. C. Boice, National Astronomical Observatory of Japan,
communicates:  "We have obtained millimeter-wave observations
resulting in upper limits on the CO and HCN column abundances in
the coma of (2060) = 95P/Chiron.  These observations were made by
T. Sekiguchi, N. Ukita, H. Hasegawa, and D. C. Boice during Feb.
10-18 UT using the 45-m radio telescope (+ AOS spectrometer) at
Nobeyama Radio Observatory (NRO).  Chiron was at mean distances of
r = 9.32 AU and Delta = 9.40 AU during our observations.  We
observed the CO (J = 1-0) transition at 115.271204 GHz (2.6 mm) and
the HCN (J = 1-0) transition at 88.6318473 GHz (3.4 mm).  We
achieved the following 3-sigma upper limits of (antenna temperature
* velocity), obtained from a total integration time of 7h50m: 0.043
K km/s for CO and 0.012 K km/s for HCN.  Assuming that Chiron's
coma fills the NRO beam (18" for HCN and 14".3 for CO), and that
the gas-excitation temperature is 8.8 K, these upper limits
correspond to an average CO column density in the beam of < 2.1 x
10E13 cmE-2 and an average HCN column density of < 1.4 x 10E10.  A
Haser-model calculation, assuming an isotropic coma expansion
velocity of 0.45 km/s and a CO linewidth twice the coma expansion
velocity, implies upper limits of the gas-production rate of Q(CO)
< 3.8 x 10E28 sE-1 and Q(HCN) < 3.3 x 10E25 sE-1, if CO and HCN are
parent molecules.  If CO originates isotropically from subsurface
layers, then the upper limit on the specific gas production rate is
Z(CO) < 3.7 x 10E13 cmE-2 sE-1.  Other searches for CO activity on
Chiron are encouraged to aid in constraining models of activity on
this peculiar object."

                      (C) Copyright 1999 CBAT
1999 May 25                    (7179)            Daniel W. E. Green

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