A FILAMENT-associated TWO-RIBBON FLARE, often occurring in spotless regions. The flare presumably results from the impact on the CHROMOSPHERE of infalling FILAMENT material.
ON-LINE GLOSSARY OF SOLAR-TERRESTRIAL TERMS of National Geophysics Data Center

A filament-associated two-ribbon flare, often occurring in spotless regions. The flare is generally slow (30-60 minutes rise time in H alpha and x-ray) and follows the disappearance of a quiescent filament. The flare presumably results from the impact on the chromosphere of infalling filament material. The Hyder flare is named for Dr. C. Hyder, who published studies of such flares in 1967.