Cyg X-3
We carried out a monitoring program to study the flare variability of the radio emission of X-ray sources. Results of daily observations of the binary systems Cyg X-3 using the RATAN-600 radio telescope from May 21 to July 20, 1997 are presented. Two short, moderate (~1 Jy), optically thick flares were detected on May 22 and May 26 at six frequencies (0.96, 2.3, 3.9, 7.7, 11.2, and 21.7 GHz). The flux decay of the second flare was exponential. After this flare, there was a sharp decrease in the radio intensity on May 29--31, to 15--20 mJy at 4--11 GHz, 10--12 days before a powerful flare on June 12 (~4 Jy). In this flare, the flux density of Cyg X-3 rose from the quiescent level by a factor of 20--30 over 1--2 days. We found the signifficant correlation of the radio flux and hard X-ray (BATSE data) radiation and anti-correlation of the radio flux and soft X-ray (RXTE ASM data) radiation during the powerful flare.