Observation of solar cosmic rays during the flare of April 29, 1973.

Combined satellite (Cosmos-555) and stratospheric observations of solar protons associated with the flare of Apr. 29, 1973 were carried out. This was a time of increased magnetic activity (the Kp index reached a value of 6-7); disturbances were observed in the radio frequency range (noise storms and separate radio bursts) and increased solar X-ray emission intensity was reported. A sharp increase in the intensity of protons with energies of between 10 and 60 MeV was observed at 21 h UT and reached a maximum in 5 h. Graphs for the time dependence and energy spectra of the protons are presented.