Central Bureau for Astronomical Telegrams
IAUC 5012: 1989c1
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Circular No. 5012
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 AUSTIN (1989c1)
M. J. Mumma, S. Hoban, M. Di Santi, D. C. Reuter, F. Espenak,
G. Chin, and D. A. Glenar, Goddard Space Flight Center; and H. A.
Weaver, Space Telescope Science Institute, report: "Infrared spectra
were obtained with the CRSP spectrometer on the 1.27-m telescope
at Kitt Peak National Observatory on May 4.5-7.5 UT. A survey
spectrum (2.9-3.8 microns; 0.018 micron/pixel) on May 4.5 revealed a
strong emission feature at 3.4 microns, with intensity contrast of
about 1.4:1 relative to the nearby continuum, based on preliminary
atmospheric correction. Spectra of the 3.45- to 3.65-micron region
(0.00333 micron/pixel) were acquired on May 5.5, 6.5, and 7.5.
These show an emission feature at 3.52 microns (0.03 micron FWHM)
whose peak intensity (450 mJy in 3-pixels totalling 8".1 x 2".7,
and centered on the nucleus) is 100 mJy brighter than the nearby
continuum. The integrated excess intensity is 8 x 10E-16 W mE-2.
H2CO is not discernible in the spectra, and a preliminary reduction
(based on T(rot) = 50 K) provides Q(H2CO) < 2 x 10E27 molecules/s
(3-sigma stochastic limit) on May 6.5."
M. C. Festou, Besancon Observatory; M. F. A'Hearn, University
of Maryland; and S. A. Budzien, P. D. Feldman, and E. E. Roettger,
Johns Hopkins University, report: "Comet Austin was observed with
the International Ultraviolet Explorer during the period May 7-13
UT. The ultraviolet spectrum is characteristic of non-dusty comets.
The variation with heliocentric distance of the extended emissions
appears to follow rE-n, where n about 2. From the OH emission
brightness, the water production rate on May 9.37 was derived to be
1.1 x 10E29 sE-1. Quick-look analysis on May 13.7 indicates a
comparable water production rate on that date. The CO fourth
positive system was detected, and a preliminary analysis of the data
indicates a CO-to-water ratio between 1 and 3 percent on May 9.
Photometry using the IUE Fine Error Sensor (the FES bandpass of
380-650 nm including emissions of CN, C2, and continuum) follows an
rE-3.8 power law during this period."
Further total visual magnitude estimates: May 11.15 UT, 4.9 (A.
Pereira, Linda-a-Velha, Portugal, 9x34 binoculars); 13.43, 5.3 (C. S.
Morris, Pine Mountain Club, CA, 10x50 binoculars; faint 2 deg tail);
14.44, 5.2 (Morris; faint 2 deg tail); 15.04, 5.2 (P. Schmeer,
Bischmisheim, W. Germany, 20x80 binoculars; 1.5 deg tail in p.a. 285
deg); 15.89, 5.5 (A. Pearce, Scarborough, W.A., 20x80 binoculars).
Corrigendum. On IAUC 5010, line 5, for 8".25 read 8'.25
1990 May 16 (5012) Daniel W. E. Green
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