Variability of Hubble-Sandage objects in M 31 and M 33.

Results are presented of a photometric study of luminous blue variables known as Hubble-Sandage objects in M 31 (V 19 = AF And, AE And, V 15, and VA 1) and in M 33 (Var A, Var B, Var C, Var 2 = Y Tri, Var 83, and GR 290). The characteristics of the light curves of the variables obtained up to 1989 were found to vary considerably. Generally, the irregular light variations have an amplitude of about 2-3 m, but amplitudes of some variables were found to exceed 5 m. Some variables displayed a systematic decrease of luminosity during the history of their observations. It was found that the maximal luminosity of some variables may reach 15 m. The luminosity changes are accompanied by changes in color.