TeV Gamma-ray Observations of Markarian 421 using TACTIC during 2009-10

Abstract

We have observed the blazar Markarian 421 with the TACTIC ${\hat{I}}^3$-ray telescope at Mt. Abu, India, from 22 November 2009 to 16 May 2010 for 265 hours. Detailed analysis of the data so recorded revealed presence of a TeV ${\hat{I}}^3$-ray signal with a statistical significance of 12.12$\ddot{I}ƒ$ at $E_{\hat{I}}^3\ge$ 1 TeV. We have estimated the time averaged differential energy spectrum of the source in the energy range 1.0 - 16.44 TeV. The spectrum fits well with the power law function of the form ($dF/dE=f_0{E}^{-\hat{I}“}$) with $f_0=(1.39\pm 0.239)\times 10^{-11}c{m}^{-2}{s}^{-1}Te{V}^{-1}$ and $\hat{I}“=2.31\pm 0.14$.

15 pages, 7 figures: Accepted for publication in J. Phys. G: Nucl. Part. Phys