The 3B/X3 solar flare of 27 February 1992

Abstract

Active region NOAA 7070 was related to a 3B/X3 solar flare that occurred on February 27, 1992. The soft X-ray flare observations were obtained by the SXT (Soft X-ray Telescope) on board the Yohkoh satellite, and those in Há from the Udaipur Observatory. The location of the Há kernels and ribbons, and the shape of soft X-ray loops are compared with the magnetic field model of the AR. Both, observations and model, suggest that the coronal loops are highly sheared before the flare and that the configuration relaxes after energy release. We compute the magnetic free energy at 2×1032 erg; this value is typical for the energy released by solar flares.