Central Bureau for Astronomical Telegrams
IAUC 4971: DW UMa; 1989c1
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Read IAUC 4972
Circular No. 4971
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
DW URSAE MAJORIS
F. V. Hessman, Max-Planck-Institut fur Astronomie, Heidelberg,
reports: "The eclipsing cataclysmic variable DW UMa (PG 1030+590)
has entered a previously-unseen low state. Rough brightness
estimates indicate B and R magnitudes of 17 and 18, roughly 2-3 mag
lower than normal (Shafter, Hessman, and Zhang 1988, Ap.J. 327, 248).
H-alpha is still singly peaked and has an equivalent width similar
to that during the normal state but has become much narrower. He II
468.6 nm, previously as strong as H-beta, has disappeared altogether.
High-resolution, time-resolved spectroscopy made with the Cassegrain
Twin-Spectrograph on the Calar Alto 3.5-m reflector shows line
profiles reminiscent of the low-state of TT Ari (Shafter et al. 1985,
Ap.J. 290, 707). Crude relative photometry made with a slit star
shows the system to be highly variable, enough to mask whatever eclipses
are still present in the spectra. Very low photometric excursions
and the faintness of the system in the near-infrared indicate that
neither the white dwarf nor the secondary star contribute significantly
to the optical spectrum. Unlike TT Ari, DW UMa normally has 20-
min 1.5-mag eclipses, so high-speed photometry and polarimetry may be
able to shed considerable light on the structure of the inner disk
during a period of substantially smaller (though not negligible)
accretion rates."
COMET AUSTIN (1989c1)
J. Manfroid, C. Gouiffes, and P. Bouchet, European Southern
Observatory, report the following Stromgren photometry of comet Austin
obtained at La Silla with the ESO/SAT 0.50-m telescope between Feb.
12 and 25. These data supersede the preliminary (on-line) reductions
on IAUC 4962; they are good to +/- 0.15 in u, +/- 0.10 in v, +/- 0.06
in b, and +/- 0.03 in y. Diaphragm 240": Feb. 13.0 UT, u = 10.95, v
= 10.11, b = 8.83, y = 8.61; 15.0, 10.54, 10.01, 8.73, 8.55; 16.0,
10.21, 9.84, 8.55, 8.44; 17.0, 10.52, 10.01, 8.63, 8.50; 18.0, 10.43,
9.98, 8.56, 8.40; 21.0, 10.41, 9.88, 8.40, 8.24; 22.0, 10.27, 9.79,
8.33, 8.17; 23.0, 10.16, 9.75, 8.26, 8.09; 24.0, 10.22, 9.69, 8.20,
8.04; 25.0, 10.11, 9.62, 8.18, 8.03. Diaphragm 35": Feb. 12.0,
12.36, 11.56, 11.03, 10.75; 13.0, 12.64, 11.69, 11.05, 10.76; 15.0,
12.32, 11.72, 10.87, 10.59; 16.0, 12.05, 11.37, 10.79, 10.53; 17.0,
12.30, 11.34, 10.73, 10.46; 18.0, 12.12, 11.29, 10.65, 10.39; 21.0,
11.91, 11.16, 10.57, 10.31; 22.0, 12.21, 11.22, 10.51, 10.27; 23.0,
11.86, 11.03, 10.33, 10.08; 24.0, 11.97, 11.09, 10.35, 10.11; 25.0,
11.95, 10.98, 10.28, 10.05. Diaphragm 17": Feb. 16.0, 13.34, 12.33,
11.86, 11.57; 17.0, 13.59, 12.38, 11.90, 11.51.
1990 February 27 (4971) Daniel W. E. Green
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