Observations of giant outbursts from Cygnus X-1

We present interplanetary network localization, spectral, and time history information for 7 episodes of exceptionally intense gamma-ray emission from Cygnus X-1. The outbursts occurred between 1995 and 2003, with durations up to ∼28000 seconds. The observed 15 300 keV peak fluxes and fluences reached 3 × 10−7 erg cm−2s−1 and 8 × 10−4 erg cm−2 respectively… (More)