Abstract:
We have studied the evolution of the double-ribbon, spotless flare of 21 February, 1992, using Kodaikanal Hagr and Kf1 observations. The analysis of the data shows that the Hagr filament underwent a large change in shear prior to the day of the onset of the flare. We find considerable rotation of the plage region before the emergence of a small magnetic pore. It is concluded that shear plays an important role in the triggering of a spotless flare
