Central Bureau for Astronomical Telegrams
IAUC 5957: N Cas 1993; (2060)
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Circular No. 5957
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
NOVA CASSIOPEIAE 1993
C. Mason and R. D. Gehrz, University of Minnesota, write: "We
report infrared magnitudes for N Cas 1993 obtained on Mar. 22.9 UT
with a bolometer on the 0.76-m telescope at the O'Brien Observatory
using a 27" beam and a 34" throw: K = 4.6 +/- 0.16, L = 1.23 +/-
0.02, M = -0.06 +/- 0.01, [8.7 microns] = -1.16 +/- 0.19, [9.8
microns] = -1.28 +/- 0.17, [10.3 microns] = -0.82 +/- 0.31. The
measurements conform to a 690-K blackbody and show that dust is
present in the ejecta. The relatively low grain temperature
suggests that the dust condensed some time ago."
Further photoelectric photometry by H. Mikuz, Ljubljana,
Slovenia (cf. IAUC 5945): Mar. 11.78 UT, V = 15.99 +/- 0.05.
(2060) CHIRON
M. P. Womack, Northern Arizona University; and S. A. Stern,
Southwest Research Institute, report: "We have obtained millimeter-
wave observations resulting in upper limits on the CO column
abundance in the coma of (2060) Chiron. These observations were
made during Feb. 25-26 UT using the Caltech Submillimeter
Observatory on Mauna Kea; we observed the CO J = 2-1 transition at
a frequency of 230 GHz (1.3 mm). Data were obtained with
resolutions of both 50 and 500 kHz in good observing conditions
(i.e., tau about 0.08). We achieved 3-sigma upper limits for the
2-1 emission of 75 and 35 mK at the 50- and 500-kHz resolutions,
respectively. Assuming (i) Chiron's coma fills the 30" CSO beam
and (ii) the gas excitation, rotational, and kinetic temperatures
are all between 10 and 50 K, then for both resolutions, the upper
limit corresponds to an average CO column density in the beam of <
(3 +/- 1) x 10E13 cmE-2. A Haser model calculation, assuming an
isotropic coma expansion at velocities of 0.2-0.5 km sE-1 and
a CO line-width twice the coma expansion velocity, implies
production-rate upper limits of Q(CO) < 6.5-15 x 10E27 sE-1,
respectively, if CO is a parent molecule, and < 9.0-36 x 10E27 sE-1
if CO is the daughter product of an H_2CO parent. If the coma is
not expanding isotropically, and instead the CO J = 2-1 line widths
are much narrower (e.g., about 1/3 the coma expansion velocity),
then the derived column densities and CO production limits could be
up to five times lower."
1994 March 25 (5957) Daniel W. E. Green
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