HESS J1303-631 is one of the unidentified TeV gamma-ray sources which H.E.S.S. group discovered as a diffuse source. We observed HESS J1303-631 between February and May in 2006 with the CANGAROO-III imaging atmospheric Cherenkov telescope system. After considering the weather conditions, the total exposure is about 35 hours live-time. Estimated threshold energy based on the Monte Carlo simulation is about 1.3 TeV. Analysis of this data set yields more than 4 sigma excess events from the direction of HESS J1303-631, which corresponds to ~20% Crab flux. Here we report our preliminary results of the flux and the spectrum of gamma-ray emission from this target object.

CANGAROO team

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 2 (OG part 1), pages 597-600