  Context: The nearby (z=0.031) TeV blazar Mrk421 was reported to be in a high
state of flux activity since November, 2009. Aims: To investigate possible
changes in the physical parameters of Mrk421 during its high state of activity
using multiwavelength data. Methods: We have observed this source in bright
state using High Altitude GAmma Ray (HAGAR) telescope array at energies above
250 GeV during February 13 - 19, 2010. Optical, X-ray and gamma-ray archival
data are also used to obtain the SEDs and light curves. Results: Mrk421 was
found to undergo one of its brightest flaring episodes on February 17, 2010 by
various observations in X-rays and gamma-rays. HAGAR observations during
February 13 - 19, 2010 at the energies above 250 GeV show an enhancement in the
flux level, with a maximum flux of ~ 7 Crab units being detected on February
17, 2010. We present the spectral energy distributions during this flaring
episode and investigate the correlation of the variability in X-ray and
gamma-ray bands. Conclusions: Our multiwavelength study suggests that the flare
detected during February 16 and 17, 2010 could arise due to a passing shock in
the jet.
