Blazar observations above 60 GeV: The influence of CELESTE’s energy scale on the study of flares and spectra Original Research Article

The CELESTE atmospheric Cherenkov detector ran until June 2004. It has observed the blazars Mrk 421, 1ES 1426 + 428 and Mrk 501. We significantly improved our understanding of the atmosphere using a LIDAR, and of the optical throughput of the detector using stellar photometry. The new data analysis provides better background rejection. We present our light curve for Mrk 421 for the 2002–2004 season and a comparison with X-ray data and the 2004 observation of 1ES 1426 + 428. The new analysis will allow a more sensitive search for a signal from Mrk 501.