Magnetic changes observed in a solar flare

We present observations of a fairly large impulsive flare (1B/M4, starting 17:22 UT, 1980 April 10). Observations of the microwave/hard X-ray burst show the time development of the impulsive energy release. Chromospheric (Hα) and photospheric (Fe I lambda5324) filtergrams and photospheric (Fe I lambda8688) magnetograms, intensitygrams, and velocitygrams show magnetic strucutre, flare emission, mass motion, and magnetic changes. From these observations, we conclude: 1. The flare was triggered by a small emerging magnetic bipole. 2. The peak impulsive energy release occurred in the explosive eruption of a filament from over the magnetic inversion line. Hence: a) The filament eruption was the magnetic transient in the heart of the primary energy release in the chromosphere and corona. b) The primary energy release did not occur in approximately stationary magnetic loops, but on field lines undergoing violet motion and drastic changes in direction. 3. In the photospheric magnetograph lines. Fe I lambda5324 and Fe I lambda8688, the impulsive peak of the flare produced emission in a unipolar area of a sunspot. In synchrony with the emission, the polarity of this area transiently reversed in the lambda8688 magnetigrams; apparently, this was an artifact of the line emission. 4. Within a few minutes after the explosive filament eruption. a) A permanent decrease in magnetic flux accompanied the truncation of an umbra. b) A permanent increase in magnetic flux accompanied the severance of the penumbral bridge to a satellite sunspot. Apparently, thee genuine photospheric magnetic changes were consequences of strong flare-wrought magnetic changes in the chromospher and corona