Central Bureau for Astronomical Telegrams
IAUC 4786: V404 Cyg = GS 2023+338
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Circular No. 4786
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
V404 CYGNI = GS 2023+338
F. Makino telexes: "Ginga x-ray observations will be conducted
during June 1.75-5.12 UT. Simultaneous observations at optical and
other wavelengths are encouraged. Ginga coverage will be for about 30
percent of the total time. For exact coverage time, contact me at ISAS,
3-1-1, Yoshinodai, Sagamihara 229, Japan (FAX 81-427-59-4253, telephone
81-427-3911 extension 2621, telex 34757 ISASTRO). X-rays from the
source were observed with the Ginga large area counters on May 23 and
28, the maximum intensity of 17 Crab being around May 28.174 UT. The
dynamic range of the erratic intensity variations was higher than 500.
The spectrum consisted of more than two components and exhibited
complicated variations combined with large changes in the density of the
absorbing material."
R. M. Wagner, Ohio State University; and S. Starrfield, Arizona
State University, report: "Optical spectra (range 400-468 nm, resolution
0.2 nm) obtained with the Perkins 1.8-m telescope at the Lowell
Observatory on May 28.4 UT show H gamma, He I 447 nm, H delta and H
epsilon in emission. In addition, the interstellar absorption feature
at 443 nm is present. The FWHM of H gamma is about 1000 km/s, corrected
for instrumental resolution. There is a single peak with broad wings.
These features, plus the features reported on IAUC 4783, suggest that we
are viewing an outburst similar to that of V616 Mon (A0620-00) but that
our spectra resemble those of V616 Mon obtained two to three weeks after
maximum (cf., e.g., Whelan et al. 1977, M.N.R.A.S. 180, 657). This is
consistent since the 1938 outburst of V404 Cyg took 60 days to fall
three magnitudes, while V616 Mon took nearly 200 days to fall this
amount. In addition, the sharpness of the emission lines suggests that
we are viewing this system more nearly pole-on as compared to V616 Mon.
However, it is also necessary to point out that these spectral features
resemble those of the recurrent nova U Sco near maximum (cf. Barlow et
al. 1981, M.N.R.A.S. 195, 61), although that object was not seen as an
x-ray source at either its 1979 or 1987 outbursts."
Photometry by M. W. Buie and H. E. Bond, Space Telescope Science
Institute, on May 30.323 UT with the 1.5-m telescope at Cerro Tololo
gave V = 12.7, B-V = +1.5, U-B = +0.3, indicating strong interstellar
reddening. High-speed photometric monitoring showed strong flickering
(up to 0.7 mag peak to peak) over timescales of a few minutes.
J. Johnson, T. Harrison and R. D. Gehrz, University of Minnesota,
report the following infrared data, obtained with the Wyoming 2.3-m
telescope on May 29: J = 9.0, H = 8.3, K = 7.7, L' = 7.2 (uncertainty
+/- 0.05 mag). High-resolution spectra showed no features.
1989 May 31 (4786) Brian G. Marsden
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