349-pixel TACTIC imaging telescope
The TACTIC (TeV Atmospheric Cherenkov Telescope with Imaging Camera) gamma-ray telescope has been in operation at Mt. Abu (24.6 degree N, 72.7 degree E, 1300m asl), India, for the last several years to study TeV gamma-ray emission from
celestial sources. The telescope uses a tessellated light collector of area ~ 9.5 meter square which is capable of tracking a celestial source across the sky. The telescope deploys a 349-pixel imaging camera, with a uniform pixel resolution of ~0.3 degree and an ~ 6 degree X 6 degree field-of-view, to take a fast snapshot of the atmospheric Cherenkov events produced by an incoming cosmic ray particle or a gamma-ray photon with an energy above ~1TeV. Using a trigger field-of-view of 11 X 11 pixels (~3.4 degree X 3.4 degree), the telescope records a cosmic ray event rate of ~2.5Hz at a typical zenith angle of 15 degree. The consistent detection of a steady signal from the Crab Nebula above ~1.2 TeV energy, at a sensitivity level of ~5.0 sigma in ~25 h, alongwith excellent matching of its energy spectrum with that obtained by other groups, reassures that the performance of the TACTIC telescope is quite stable and reliable. Furthermore, encouraged by the detection of strong gamma-ray signals from Mrk 501 (during 1997 and 2006 observations) and Mrk 421 (during 2001 and 2005-2006 observations), we believe that there is considerable scope for the TACTIC telescope to monitor similar TeV gamma-ray emission activity from other active galactic nuclei on a long-term basis.
Back-end signal processing electronics used in the telescope
Data Acquisition System Screen