Was the Crab seen by the ASGAT telescope

The ASGAT gamma ray telescope, located 1700 m a.s.l. in the French Pyrenees, was fully operational by the end of 1989. The Crab nebula was tracked for 22 hours in December ’89 and January ’90. Fast timing information from the 7 mirrors array was used to reconstruct the arrival direction of each event with an accuracy better than a degree. A special data analysis, designed to keep reliable control of the cosmic background, was tailored leading to the detection of a gamma ray signal from the Crab direction, with a flux of 3.4±1.5×10−11 cm−2 s−1 above 500 GeV. The realiability of this 2.3σ result is discussed.