X-Ray/Optical/Infrared/Radio Observations

With reference to IAUC 3652, W. H. G. Lewin communicates the following Hakacho observing schedule for 1982 Mar.-Aug.: Now-Apr. 12: Cen X-3, GX 304-1, GX 301-2 (this source expected to go from low to high state near Apr. 8 +/- 3), Her X-1; Apr. 13-30: Galactic center, Rapid Burster MXB173O-335, 4U/MXB 1735-44, GX 1+4; May 1-12: GX 304-1, GX 301-2; May 14-25: GX 339-4, Cir X-1; May 27-June 9: 4U/MXB1636-53 (there is some evidence from observations during the past three years that the time delay between optical and x-ray bursts varies; further simultaneous observations could perhaps establish this); June 10-20: 4U/MXB1636-53, Her X-1; June 21-30: 4U/MXB1636-53; July 1-20: Galactic center, MXB1730-335, 4U/MXB1735-44, GX 5-1 (no optical counterpart known), GX 1+4; July 21-Aug. 20: GX 17+2 (optical counterpart uncertain; see IAUC 3620; x-ray bursts have been observed; see IAUC 3624, 3628). On request, only one object (or more) in the above options could be observed during the periods indicated; this schedule can also be changed (if spacecraft constraints permit). Observers should contact Lewin at M.I.T. (see IAUC 3652) or the Hakucho Team (M. Oda), Institute of Space and Astronautical Science, 4-6-1 Komaba, Meguro-Ku, Tokyo 153, Japan (telephone Japan 03-467-1111, telex Japan 24550 SPACETKY J, cables SPACETKY TOKYO JAPAN). The x-ray observations are made for a total of ~ 5 hr per day. The exact times (in UT) of the x-ray observations will be available about two weeks prior to the observations, and they will be telexed to observers if requested.