Central Bureau for Astronomical Telegrams
IAUC 3482: 2A 0526-328; HEAO Obs OF X-RAY SOURCES
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Circular No. 3482
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
2A 0526-328
J. van Paradijs, E. P. J. van den Heuvel and F. Verbunt, Astronomical
Institute, University of Amsterdam, write: "We made
spectroscopic observations of the optical counterpart of 2A 0526-328
(IAUC 3298) with the image-dissector scanner on the 3.6-m telescope
at the European Southern Observatory during 1979 Nov. 10.255-10.361
11.335-11.358 and 14.111-14.341 UT. The spectra show Balmer lines
He I 447.1-, 492.1-, 501.6-, 587.6-nm and He II 468.6-nm in emission,
with variable strength. The behavior of H-beta agrees with the
results of Watts et al. (1980; M.N. 191, 25P), showing a rather
sharp rise of the equivalent width from 1.2 to 2.3 nm (within 1
hour), and a slower decay (in 2 hours) to 1.2 nm, at which value it
remains for 2 hours. These H-beta variations support the period of
5.186 hours proposed by Motch (IAUC 3427). There is much less
clear variation when the data are folded with the possible
4.26-hour period, which Motch could not exclude. The radial velocity
for H-beta shows a regular variation with a total amplitude of 120 km/s.
This is considerably smaller than the radial-velocity variations
found by Watts et al. However, the relative phasing of H-beta radial
velocity and linestrength is in agreement with their results."
HEAO OBSERVATIONS OF X-RAY SOURCES
N. E. White, S. S. Holt, E. A. Boldt and P. J. Serlemitsos,
Goddard Space Flight Center, write that HEAO 1 and 2 observations in
1978 and 1979 have confirmed the x-ray fluxes of three x-ray sources
to be modulated with periods as follows:
4U 1822-37: 5.57-hour period (cf. IAUC 3406). The light curve
is to first order sinusoidal with a peak-to-mean amplitude of 25
percent and the minimum centered on photometric phase ~ 0.8. In addition,
there is a sharp feature from phase 0.0 to 0.09 wherein the
flux drops to 75 percent of the other minimum.
2A 0311-227: 81-min period (cf. IAUC 3324). The light curve is
sinusoidal with a peak-to-mean amplitude of 40 percent and maximum
centered on linear-polarization phase 0.5 (cf. IAUC 3327). In addition,
there is an absorption dip from phase 0.40 to 0.47.
4U 2129+47: 5.3-hour period (cf. Ulmer et al. 1980, Ap.J. 235,
L159). The light curve is basically the same as that reported by
Ulmer with in addition a secondary minimum at phase ~ 0.6 about
three times less deep than the primary minimum.
1980 June 6 (3482) Brian G. Marsden
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