IREM Observations of the Initial Spike from the SGR1806‐20 Giant Flare

Main spike of the giant flare from SGR1806‐20 (27 Dec 04) released enormous energy that saturated most X‐ray detectors onboard satellites. Fortunately, several smaller instruments dedicated mainly for charged particle detection could gather reliable data. To date, spike fluences from various detectors agree within a factor of 3 while the spectra are described using different formulas. To the analysis performed with particle detectors from RHESSI and Wind we add new data provided by IREM monitor onboard of INTEGRAL. It supports cooling blackbody spectrum with temperature of 230±50 keV and energy of 0.97±0.50 erg/cm2.