Astronomy Letters -- January 2000 Volume 26, Issue 1, pp. 1-60 ART-P/Granat Observations of the X-ray Pulsar 4U0115+634 during the Outburst in February 1990 A. A. Lutovinov, S. A. Grebenev, and R. A. Sunyaev pp. 1-8 Full Text: PDF (188 kB) One Hundred Years of Observations of the Be Star HDE 245770 (the X-ray Binary A0535+26/V725 Tau): The End of an Active Phase? V. M. Lyuty and G. V. Zaitseva pp. 9-21 Full Text: PDF (182 kB) Variability of Cyg X-1 (V1357 Cyg) in 1995–1996 during the Hard and Soft X-ray Spectral States E. A. Karitskaya, V. P. Goranskii, K. N. Grankin, and S. Yu. Mel'nikov pp. 22-33 Full Text: PDF (237 kB) A Flare of the H2O Maser in the Source Orion KL A. M. Tolmachev pp. 34-37 Full Text: PDF (61 kB) Determining the Period of the Long-Period Activity of the Water-Vapor Maser in W75N E. E. Lekht and V. V. Krasnov pp. 38-48 Full Text: PDF (297 kB) On the Stability of the Phase Problem V. Yu. Terebizh pp. 49-60 Full Text: PDF (291 kB)