Photospheric and Chromospheric Activity Associated with 3B Flare of February 27, 1992

We have analyzed the H filtergrams and vector magnetograms of the active region NOAA 7070, in which a 3B/X3.3 flare occurred on February 27, 1992. The average area per sunspot of this active region was in declining phase at the time of the flare. The vector magnetograms indicate that the magnetic field was non-potential at the flaring site. Besides non-potentiality, the longitudinal field gradient was found to be the highest at the region showing initial H brightening. Further, in H filtergrams no appreciable change in the morphology of the filament tracing the magnetic neutral line was noticed in the post-flare stage. Also, the photospheric vector magnetograms show considerable shear in post-flare magnetic field of the active region. In this paper we present the observations and discuss the possible mechanism responsible for the 3B/X3.3 flare.