Optical Candidates for X-Ray Sources

N. E. Kurochkin, Sternberg Astronomical Institute, proposes CSVS 4693 (R.A. = 19h25m44s, Decl. = +42o53'.2, equinox 1900.0; Belyavskij 1936, Pulkovo Obs. Circ. No. 19) as the optical counterpart of 3U 1921+43. Moscow plates during 1949-1970 show nonperiodic variations between mpg 13.5 and 17 over intervals of a few days. H. Pedersen, University of Aarhus, suggests the identification HR 3089 = 3U 0750-49. Observations of this He-strong B-type star at the European Southern Observatory in January and February show He variability with a period of 1.3295 +/- 0.0025 days.