Some studies on rare types of microwave bursts

Microwave bursts of rare type (i.e., spike, rise, fall, absorption, etc.) recorded by various solar observatories at and about 2800 MHz for the period 1967-1976 were analyzed. Results include the following: (1) most of the rare types have peak fluxes not exceeding 15 fu; (2) the percentage of bursts associated with flares increases with increase of peak flux and also with increase of rate of change of flux; (3) burst-associated flares are mostly subflares; and (4) bursts are dominant in the declining phase of the solar cycle