The Tibet air shower array at an altitude of 4300 m (above sea level) has been in operation since January 1990. We have searched for continual emission of 10-TeV gamma rays from the Crab Nebula, Cygnus X-3, and Hercules X-1 during the period from June 1990 through January 1992. No dc excess is found from these three sources. Flux upper limits above 10 TeV are obtained to be 1.2×10-12 cm-2s-1 for the Crab Nebula, 1.1×10-12 cm-2s-1 for Cygnus X-3, and 0.58×10-12 cm-2s-1 for Hercules X-1 at the 95% C.L. This is the first observation, with an air shower array, for these sources in the 10-TeV energy region.
|Number of pages||4|
|Journal||Physical Review Letters|
|Publication status||Published - 1992 Oct 26|
ASJC Scopus subject areas
- Physics and Astronomy(all)