Central Bureau for Astronomical Telegrams
IAUC 4835: 1E 0021-72; CH Cyg; V745 Sco
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 4836
Circular No. 4835
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
1E 0021-72
C. Bailyn and A. Cool, Harvard-Smithsonian Center for Astrophysics,
report that there has been a dramatic decrease in luminosity of the star
proposed by Auriere et al. (1989, A.Ap. 214, 113) as the optical
counterpart of the x-ray source 1E 0021-72 in 47 Tuc. A sum of six U
exposures of 60 s each taken during Aug. 1.34-1.40 UT in 1" seeing with
the Cerro Tololo 4-m PF/CCD and TI No. 1 chip shows no sign of the
ultraviolet star 9 of Auriere et al. down to U = 18, or 1.7 mag fainter
than it was in 1986. The apparent strong variability of this star
further suggests that it is the optical counterpart of the x-ray source,
which may now be in a low-luminosity state.
CH CYGNI
T. Tomov, Insititute of Astronomy, Bulgarian Academy of Sciences;
A. Dapergolas, J. Bellas and E. Kontizas, Astronomical Institute,
National Observatory of Athens; and M. Kontizas, Laboratory of
Astrophysics, University of Athens, telex: "Spectroscopic observations
of the symbiotic star CH Cyg have been carried out with the 2-m
telescope of the Bulgarian National Astronomical Observatory on a
regular basis after an active phase of the star. Coude spectra
(dispersion 1.8 nm/mm, range 360-490 nm) obtained during 1987 July-1989
July have shown an M6 III star with faint, one-component emission in H
beta enhancement and one-component emission at Balmer lines up to H12.
Photometric observations with the 1.2-m Greek Kryonerion telescope
during 1989 Aug. 1-6 have shown remarkable variations in U amounting to
0.40 mag in a single night; continuous variations of the order of 0.2
mag were observed over time intervals of about 10 min."
Visual magnitude estimates: July 27.06 UT, 8.1 (P. Schmeer,
Bischmisheim, West Germany); Aug. 3.89, 8.7 (A. Pereira, Cabo da Roca,
Portugal); 5.92, 8.3 (Schmeer).
V745 SCORPII
J. Mattei, AAVSO, communicates the following visual magnitude
estimates by D. Overbeek, Edenvale, South Africa: Aug. 3.7 UT,
11.5; 4.7, 11.5; 5.7, 11.7; 6.7, 12.0; 7.7, 12.5; 8.7, 13.0.
1989 August 17 (4835) Brian G. Marsden
Read IAUC 4836
Our Web policy. Index to the CBAT/MPC/ICQ pages.
