COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                         Number 913

                                       Konkoly Observatory
                                       Budapest
                                       1974 July 29


       COOPERATIVE RADIO AND OPTICAL OBSERVATIONS
                OF CLOSE BINARY STARS

    I am currently investigating radio emission from close binary
stars. I am planning extensive observations using the NRAO Interferometer 
in the near future. This study could be greatly enhanced if
simultaneous optical observations could be secured. The objects and
dates of observation are as follows:

alpha Sco B        -   Aug 10 - 15
    R Aqr          -   Aug 10 (Aug 11-15--tentative)
 beta Lyr          -   Sept 7 - 12
 beta Per (Algol)  -   Sept 7 - 12
HDE 226868(CygX-1) -   Sept 12 - 33 (Aug 11-15--probable)
   CC Cas          -   Sept 12 - 23

Additional observations of AR Lac and b Per are tentatively planned
for late October. I will inform you of the exact dates when they 
become firm. Interested participants are requested to contact me for
further details at the following address:


July 18, 1974

                             DAVID M. GIBSON
                    National Radio Astronomy Observatory
                    Edgemont Road, Charlottesville,
                    Virginia 22901, U.S.A.