The Chandra Observations of BL Lac Markarian 421 in the High-Emission State

Markarian 421 is a well-established BL Lac-type active galactic nucleus (AGN). It is one of the brightest and extremely high variable TeV blazar. The TeV gamma-ray emission observed from this source varies in flux dramatically. In November 2009 we observed Markarian 421 for three 5-ks exposures with the Chandra X-ray Observatory during the period of its high TeV gamma-ray emission state. These observations have contributed to the broadband multi-wavelength observational campaign that involved a number of space-born and ground-based experiments. The analysis results showing the evolution of the X-ray energy spectrum across the flare will be presented at the conference.