Analysis of digital H-alpha solar flare measurements

H-alpha data from a digital solar flare measurement system using semiautomated computer-video techniques are examined. Periodically from early 1971, two systems were run simultaneously. The measurements are consistent to within 10 per cent. Many events show area enhancements in lower brightness levels minutes before the peak brightness in the region changes, indicating an initial heating phenomenon. Our data show a good correlation with Solrad 9 and 10 soft-X-ray fluxes. There is less correlation with the harder X-ray measurements. For four subflares, we have done a detailed temporal comparison with UCSD OSO-7 hard and soft X-rays. H-alpha brightening has excellent start time correlation with the soft X-ray, the point which attains maximum brightness coincides temporally with the hard X-ray burst peak, and the H-alpha peak brightness and enhancement area remain above the pre-event levels beyond the end of the hard X-ray burst.