Long-term and orbital variability of the optical spectrum of HDE 245770=A 0535+26.

Further results of investigation of the Be star HDE 245770 are presented. Strengthening of absorption and emission lines by 40 - 50 per cent in January 1981 is noted. Connection of this with the X-ray flare is discussed. The presence of periodicity with P = 34^d.5 in the intensity of the emission line Hβ is shown. The spectral class Sp = O9.90±0.10 of the star and the absolute magnitude M_v = 5^m.8 are determined. The dimensions of the envelope in the lines Hβ (r = 1.5 R_*) and Hα (r = 5 R_*) are estimated.