Central Bureau for Astronomical Telegrams
IAUC 3615: SU Cyg; V926 Sco; AM Her; 1981f
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Read IAUC 3616
Circular No. 3615
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
SU CYGNI
N. R. Evans, Department of Astronomy, University of Toronto,
writes: "The binary Cepheid SU Cyg (= HD 186688) has been shown to
have a high inclination (cf. Evans 1980, Bull. A.A.S. 12, 862) and
about a one in five chance of an eclipse. IUE observations will be
made to search for an eclipse, but ground-based observations would
also be very useful. Well-exposed plates of the H and K lines
(twice the normal exposure for plates in the 400-500-nm region for
a late F star) show that the blue companion contributes light equal
to at least 10 percent of the continuum at the K line at all phases
of the Cepheid. Eclipse of the secondary is predicted for Oct. 22
(uncertainty +/- 2 days), and a central eclipse is estimated to last
for 9 days. Suitable plates taken at this time should show clearly
whether the companion is still visible."
V926 SCORPII
J. E. McClintock and L. D. Petro, Massachusetts Institute of
Technology, report: "We have discovered a 4.3-hr modulation in the
broadband optical flux from the x-ray burst source V926 Sco (= MXB
1735-44). The full amplitude is ~ 0.2 mag. The source, a reference
star and the background were observed continuously for 9 hr beginning
June 3.05 UT, using the Cerro Tololo Interamerican Observatory's
1.5-m telescope and a scanning slit photometer. An orbital
period of 4.3 hr is consistent with an M0V star which fills its
Roche lobe."
AM HERCULIS
J. A. Mattei, American Association of Variable Star Observers,
reports that this irregular variable has begun another decline, as
seen by the following visual magnitude estimates by E. Mayer,
Barberton, OH: May 2.25 UT, 13.2 (maximum); June 2.10, 13.3; 11.14,
14.4; 23.16, 15.0; 29.12, 15.0.
PERIODIC COMET GEHRELS 2 (1981f)
A. Cochran, McDonald Observatory, informs us that the recovery
observations (cf. IAUC 3612) were made by W. Cochran and herself
with the 2.7-m reflector. The comet was of mag ~ 19.5 and had a
featureless spectrum.
1981 July 8 (3615) Daniel W. E. Green
Read IAUC 3616
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