Abstract:
We report the CaII K observations of a major umbral solar flare of optical class 3B which occurred on 1989 March 13. Correlated optical, microwave, soft X-ray (SXR), sudden ionospheric disturbance observations and the resulting proton enhancements have also been analyzed. The values of magnetic field perpendicular to electron velocity electron energy E and angular size of a great microwave burst (GB) source are estimated as 897 gauss, 1.4 MeV, and 7 arcsec, respectively. Due to the production of long-duration hard X-ray burst and GB, we conclude that the observed flare is very energetic
