The “ Gamma Ray Astronomy at ALmería ” ( GRAAL ) experiment uses 63 heliostat-mirrors with a total mirror area of \approx 2500 m ^ { 2 } from the CESA-1 field to collect Cherenkov light from airshowers .
The detector is located in a central solar tower and detects photon-induced showers with an energy threshold of 250 \pm 110 GeV and an asymptotic effective detection area of about 15000 m ^ { 2 } . Data sets taken in the period September 1999 - September 2000 in the direction of the Crab pulsar were analysed for high energy \gamma -ray emission .
Evidence for \gamma -ray flux from the Crab pulsar with an integral flux of 2.2 \pm 0.4 ( stat ) ^ { +1.9 } _ { -1.5 } ( syst ) \times 10 ^ { -9 } cm ^ { -2 } s ^ { -1 } above threshold and a significance of 4.5 \sigma in a total ( usable ) observing time of 7 hours and 10 minutes on source was found .
No evidence for emission from the other sources was seen . The effect of field-of-view restricted to the central part of a detected airshower on the lateral distribution and timing properties of Cherenkov light and their effect on an efficient \gamma -hadron separation are discussed .