Optical/X-ray Observations in 1980

W. Lewin and L. Cominsky, Massachusetts Institute of Technology, communicate: "Dark time has been made available by M. Oda on Hakucho (Japan) and may also be made available by K. Pounds on UK 6 (England) for simultaneous optical and x-ray observations of x-ray burst sources with faint optical counterparts. The periods during which the observations will be made are 1980 Apr. 9-23, May 9-23, June 7-21, July 7-21 and Aug. 7-21. The objects to be studied are MXB1636-53 (from which 15 optical bursts were recorded during the 1979 observations; cf. IAUC 3399), MXB1735-44 (IAUC 3230), MXB1837+05 (IAUC 3331), and possibly MXB1659-29 (IAUC 3190, 3229), 4U 1608-52 (IAUC 3349) and Cen X-4 (IAUC 3362, 3366), depending on burst activity. Participation by optical observers is invited. Large telescopes (apertures ~ 1.5 m or larger) are needed because the optical counterparts are faint (mv > 17). Astronomers who are interested in participating should contact us (telephone 617-253-4282, telex 92-1473 MIT CAM, TWX 710-320-0058 MIT CAM)."