Central Bureau for Astronomical Telegrams
IAUC 5081: 1990c
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Circular No. 5081
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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
COMET LEVY (1990c)
P. D. Feldman, S. A. Budzien, Johns Hopkins University, and
M. F. A'Hearn, University of Maryland, report observations of comet
Levy with the International Ultraviolet Explorer between Aug.
26.103 and 26.364 UT: "Photometry using the IUE Fine Error Sensor
showed a 33-percent increase in brightness to a maximum at Aug.
26.333. Long-wavelength spectra obtained over this interval showed
a 13-percent increase in OH flux at 309 nm, a 21-percent increase
in the CS flux at 258 nm, and a 31-percent increase in ultraviolet
continuum at 295 nm, suggesting that the FES is responding primarily
to visible dust emission. A mean water production rate of 3 x
10E29 sE-1 is derived using a vectorial model with photodissociation
lifetimes appropriate to solar maximum. The CO fourth positive
system was detected in the short-wavelength spectrum and a
preliminary analysis gives a CO production rate of 1 x 10E28 sE-1."
P. Schloerb and W. Ge, University of Massachusetts, write: "We
report the detection of the 266-GHz HCN J = 3-2 transition at the
Caltech Submillimeter Observatory on Mauna Kea. The line was easily
detected with an antenna temperature of 0.5 K. The integrated
intensity of the line on the nominal position of the nucleus is 1.00
+/- 0.03 K km sE-1, which corresponds to an HCN production rate of
approximately 5 x 10E26. We were also able to map the line over a
1'.5 region. The HCN brightness distribution is quite asymmetric,
with the emission more extended to the west (sunward) and south of
the nucleus."
D. G. Schleicher, R. L. Millis, and D. J. Osip, Lowell Observatory,
report: "Narrowband photometry taken at Lowell Observatory on
10 consecutive nights beginning Aug. 18 has revealed clear-cut,
quasi-periodic variations in the comet's level of activity. The
period of these variations is 18.9 +/- 0.2 hr (or twice this value
if there are two maxima rather than one per cycle). The amplitude
of variation in production rates ranges from 35 percent for C3 to 20
percent for dust, using a 38"-diameter entrance aperture. Mean
Haser model production rates for the various species sampled were:
log Q(OH) = 29.41, log Q(CN) = 26.54, log Q(C2) = 26.51, log Q(C3) =
25.31, and log Q(NH) = 26.75. The dust production rate (cf. IAUC
4983) was log (A f rho) = 3.85."
1990 August 29 (5081) Daniel W. E. Green
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