CAT AND CELESTE - GAMMA-ASTRONOMY AT THEMIS

Two independent sampling arrays, THEMISTOCLE and ASGAT, were installed in 1988 on the site of a former power solar, ''Themis'', in the frenc h Pyrenees. Shortly after the discovery of the TeV gamma-ray emission from the Crab Nebula by the imaging telescope of the Whipple Observato ry, the ''Themis'' arrays confirmed these observations and extended th em to higher energies. They are now interconnected with a new imaging telescope whose expected energy threshold is about 200 GeV. This last device is under commissioning at the time of this Symposium. The compl ete setup is named ''CAT'' for ''Cherenkov Array at Themis''. Furtherm ore, the overall Themis solar plant will soon be reactivated as a gamm a-ray detector, most of its heliostats back to operation, a large seco ndary mirror taking the place of the solar furnace. This approved CELE STE project will represent a further step towards low energies, hopefu lly closing the gap between space and ground-based observations.