Mrk 421 and 501 above 60 GeV: the Influence of CELESTE's Energy Scale on the Study of Flares and Spectra

The CELESTE atmospheric Cherenkov detector ran until June 2004. It has detected several gamma-ray flares of Mrk 421 since 1999. The new data analysis provides better background rejection. We compare our light curves with X-ray data. We significantly improved our understanding of the atmosphere, and of the optical throughput of the detector. This will allow a spectral measurement for Mrk 421 with smaller uncertainties and a more sensitive search for a signal from Mrk 501.