Study of a Great Microwave Burst on December 16,1988

A rare microwave type Ⅳ burst was observed with Phoenix ⅠCorona-Radiospectrometer at Yunnan Observatory(1.42GHz、2.84GHz and 4.00GHz) from 08h31m to 09h41m UT on December 16,1988.The type Ⅳ burst was extended from the metric wave to the microwave bands. The burst long duration,high intensity and complex morphology.Five main peaks appeared from beginning to the end. A short period oscillation of 1.2 minutes and a long period oscillation of 12.5 minutes were observed.Many fine structures of spike were superimposed on type Ⅳμ bursts of two frequencies (1.42GHz and 2.84GHz).According to the twist-oblique magnetic field configuration,by using the magnetic-trap model,we have computed the equivalent temperature of the source region,the magnetic field varied with the height and the peak frequency appeared at 8.89GHz.This result indicats that the type Ⅳμ burst was generated from the gyro-synchrotron radiation of high energy electrons trapped by the magnetic field.