Signs of Preparation of Solar Flares in Microwave Range

Abstract

We present a study of the spatial distribution of quasiperiodic oscillations of microwave emission in active region 11302 before the M4.4 flare on September 25, 2011. We used the Nobeyama Radioheliograph (NoRH) daily observations at 1.76 cm. We found that the oscillations are localized in a compact zone of the active region, which coincides with the place of maximum brightness during a flare.