COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 728


                                 Konkoly Observatory
                                 Budapest
                                 1972 October 19



                ANNOUNCEMENT



    The dates for the simultaneous searches for rapid
(time scales < 24h) variations in the optical, IR and
radio emission from 3C 120, OJ 287, and BL Lac [see
Information Bulletin No. 687 and Astrophys.J. (Letters)
178, L61, 1972 (Dec. 1)] have been set for 1972 Dec. 2/3-
8/9 [BL Lac (first half of night) and 3C 120 (second
half of night)] and 1973 Feb. 1/2 - 7/8 (OJ 287). At least
33 groups plan to participate. Interested observers should
write to Eugene E. Epstein, The Aerospace Corporation,
Box 92957, Los Angeles, Calif. 90009.



                        EUGENE E. EPSTEIN
                        Radio Astronomy Program
                        120/2101