Comparison Of VSB From BATSE, KONUS And SWIFT

We show the locations of the SWIFT short hard bursts (SHB) with afterglows on the Galactic map and compare with the very short bursts (VSB) BATSE events. As we have pointed out before, there is an excess of events in the Galactic map of BATSE VSB events. We note, that none of VSB SWIFT era events fall into this cluster. More SWIFT events are needed to check this claim. We also report a new study with KONUS data of the VSB sample with an average energy above 90 keV showing a clear excess of events below 100 ms duration (T90) that have large mean energy photons. We suggest that VSB themselves consists of two subclasses: a fraction of events have peculiar distribution properties and have no detectable counter parts, as might be expected for exotic sources such as Primordial Black Holes. Detection of VSBs in GLAST could help this process.