Magnetic fields, bremsstrahlung and synchrotron emission in the flare of 24 October 1969

An impulsive flare October 24, 1969 produced two bursts with virtually identical time profiles of 8800 MHz emission and X-rays above 48 keV. The two spikes of hard X-rays correspond in time to the times of sharp brightening and expansion in the Hα flare. The first burst was not observed at frequencies below 3000 MHz. This cut off is ascribed to plasma cutoff above the low-lying flare. A model of the flare based on Hα observations at Big Bear shows that the density of electrons with energy above 10 keV is 5 × 10⁷ if the field density is 1011. The observed radio flux would be produced by this electron distribution with the observed field of 200 G. The Hα emission accompanying the hard electron acceleration is presumed due to excitation of the field atoms by the hard electrons