Observations of Mrk 421 and Mrk 501 in Spring 2006 with VERITAS

Abstract

VERITAS, the Very Energetic Radiation Telescope Imaging Array System, is an array of four imaging Atmospheric Cherenkov telescopes in southern Arizona. It is sensitive to gamma rays at energies above 100 GeV. Here, we discuss the results of observations of two well known VHE blazars, Markarian 421 and Markarian 501, during Spring 2006 which were made with the first two telescopes during the comissioning phase of VERITAS. During most of this time Mrk 421 was in an unusually active state while Mrk 501 was in a much lower flux state. As such, these observations provided an opportunity to test the sensitivity of the instrument to strong and weak sources. We discuss implications of these observations on our understanding of these objects.