Presentation #127.16 in the session “Solar Physics Division (SPD): Flares”.
A remarkable solar microwave (1.4 GHz) burst, SOL2019-05-06T17:47:35.385, has been reported by the STARE2 fast cosmic transient survey (Bochenek et al., 2020). Its behavior resembles that of the Fast Radio Burst (FRB) extragalactic events in having a relatively broad spectral bandwidth and brief (19-msec) duration. It also had no measureable dispersion. The associated flare, GOES class C1, had a relatively hard X-ray spectrum as observed by Fermi/GBM, but no temporal association at the msec time scale suggested by the microwaves. Although msec variability in the microwave domain has been known to solar radio astronomy since the 1970s, the brightness and isolation of this event (both spatial and temporal) suggests novelty. Accordingly we survey the available correlative data from many sources and discuss possible interpretations in terms of type III-like behavior, electron cyclotron masering, and gyrosynchrotron emission. We note that the radio data (e-Callisto and EOVSA) revealed abundant type III activity in the vicinity, and the related flares as observed by GOES had exceptionally short time scales, suggesting burst origins in the lower solar atmosphere.