Some Studies on Rare Types of Microwave Bursts

155-158Microwave bursts of rare types, viz. 'spike', 'rise', 'fall' and 'absorption', recorded by different solar observatories at and around 2800 MHz for a period of one decade (Jan. 1967-Dec. 1976) were examined. Important results obtained from this statistical investigation are: (i) most of the rare type of bursts have peak flux not more than 15 f.u., (ii) the percentage association of the bursts with flares increases with the increase of peak flux and also with the increase of rate of change of flux, (Hi) burst-associated flares are mostly subflares, (iv) spectra of the peak flux (negative) and energy absorbed, for the 'absorption' type of bursts, generally show greater absorption at higher frequencies, (v) the bursts are mostly dominant in the declining phase of the solar cycle, and (vi) the percentage association of some types of bursts with flares varies more or less linearly with the number of bursts through the whole of the solar cycle studied