Central Bureau for Astronomical Telegrams
IAUC 4962: 1989c1; EF Eri; VENUS
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Circular No. 4962
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)
P. Bouchet and R. M. West, European Southern Observatory, report:
"Infrared photometry, obtained by Bouchet, T. LeBertre and R. Vega with
the ESO 1-m telescope, gives: Jan. 18.05 UT, diaphragm 30", J = 10.81
+/- 0.03, H = 10.37 +/- 0.03, K = 10.17 +/- 0.04; Feb. 10.01, 22",
10.74 +/- 0.03, 10.26 +/- 0.03, 10.03 +/- 0.03; 10.01, 15", 11.19
+/- 0.04, 10.76 +/- 0.03, 10.65 +/- 0.03. Optical photometry was also
obtained with the 0.5-m Danish reflector by Bouchet and J. Manfroid:
Feb. 12.00 UT, diaphragm 35", y = 11.2 +/- 0.05; 13.01, diaphragm 240",
u = 11.24, v = 10.31, b = 8.73, y = 8.58; 13.01, 35", 13.45, 12.05,
11.03, 10.72."
EF ERIDANI
D. T. Wickramasinghe, Australian National University; N. Achilleos,
Mount Stromlo Observatory; K. Wu, ANU; and B. J. Boyle, University of
Cambridge, report: "Observations of EF Eri obtained with the University
College London Echelle Spectrograph on the Anglo-Australian Telescope
on Jan. 21 showed it to be in a low state for the first time since its
discovery as an AM Her variable in 1979. The spectrum showed a weak
H alpha emission feature for 20 percent of the period and a narrow
absorption feature centered at 656.00 +/- 0.02 nm, which is identifiable
as a Zeeman pi-component of H alpha arising from the white dwarf
photosphere of mean field strength 7.0 +/- 0.2 MG. The corresponding
polar field strength for a centered dipole distribution is about 9.80 MG,
making EF Eri the lowest-field AM Her. Low-resolution spectra taken the
next night (by M. A. Dopita and S. Ryder) confirmed the low state of
EF Eri via the presence of relatively weak Balmer and He emission lines."
VENUS
D. Allen, Anglo-Australian Observatory, reports the discovery of
four new windows into the atmosphere of Venus: "AAT observations of the
dark side of the planet show broad emission bands at 1.08-1.11, 1.17-1.20,
1.26-1.28 and 1.30-1.31 microns. The O2 airglow line is superimposed on
the third of these. The brightness temperature attains about 570 K,
indicating penetration to an altitude of 35 km. Surprisingly, the broken
cloud layer that causes patterns in the 1.74 and 2.3 micron windows is
almost transparent at 1.18 microns. Since other windows may exist at
shorter wavelengths, CCD spectroscopy is suggested in the next two weeks
before the growing sunlit crescent precludes dark-side observation."
1990 February 13 (4962) Gareth V. Williams
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