TeV Gamma-ray flares from Mkn 421 detected by the pachmarhi array of Cverenkov Telescopes

Abstract

Pachmarhi Array of Cverenkov Telescopes (PACT), based on wavefront sampling technique, has been used for detecting TeV gamma rays from galactic and extra-galactic ?-ray sources. The Blaar, Mkn 421 was one such extra-galactic source observed during the winter nights of 2000 and 2001. We have carried out a preliminary analysis of the data taken during the nights of January, 2000 and 2001. Results show a significant gamma ray signal from this source during both these periods above a threshold energy of 900 GeV. The source was contemporaneously observed by CAT imaging telescope during the first episode of January 2000 while HEGRA CT1 was observing the source during the second episode. Both these observations have detected variable gamma-ray emission from this source and flaring activity during both these periods has been reported. The light curve in the TeV gamma ray range derived from the first PACT observations during both these episodes is in agreement with that reported by other experiments. The analysis procedure and the preliminary results will be presented and discussed.