In IBVS 4404, E. A. Karitskaya and V. P. Goranskij report an unusual fading of V1357 Cyg (Cyg X-1) in early November, 1996. They report a transient ~0.04 mag fading in V. I wonder whether this optical fading is somehow related to the recent soft-hard transition in August, 1996 (S. N. Zhang et al. IAUC 6447).
Wouldn't it be a nice target for CCD photometrists for future X-ray-to- optical correlation study?
The so-called "soft state" of Cyg X-1 lasted from mid may to mid august. Judged from the X-ray light curves, the transition back to the so-called "hard state" was definately over by the time of the observations of Karitskaya & Goranskij in early November, 1996.
> Wouldn't it be a nice target for CCD photometrists for future X-ray-to- > optical correlation study?
It would be therefore good to monitor such optically bright X-ray binaries, in order to look for such optical transitions, and to correlate it with the X-ray behaviour.
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