Evolution of the compact microwave inter-sunspot source before strong flare

Abstract

Under this study we considered active region 09415 of the 23-rd cycle of solar activity which was observed with the 2D spatial resolution at three frequencies: 17 and 34 GHz with the Nobeyama Radioheliograph (NoRH) and 17 GHz with the Solar Siberian Radiotelescope (SSRT). We detected rapid development of a compact microwave source above the neutral line of the magnetic field of leading sunspot (NLS-source) few hours before the X-class flare. The position of this source is associated with the place of the maximum of magnetic field gradient at the photosphere.