AGILE View of TGFs

The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high energy gamma-ray astrophysics in the 30 MeV-50 GeV range, with a window in the hard-X domain 18-60 keV. One of the on-board detectors, the Mini-Calorimeter (MCAL), was also designed to work as all sky transient monitor in the energy range 0.33-100 MeV. Though the main purpose of MCAL is the detection of cosmological Gamma-Ray-Bursts (GRB), MCAL detected transient events with a very brief duration, few msec, that does not match timing and spectral features of known cosmic GRB. These events more likely agree with the features of typical Terrestrial Gamma-Ray Flashes as described in the literature and previously detected by the BATSE instrument onboard the Compton Gamma Ray Observatory and the RHESSI satellite. The characteristics of the detected TGF candidate events, as well as their geographical distribution will be presented and discussed.