Mrk 421, Mrk 501, and 1ES 1426+428 at 100 GeV with the CELESTE Cherenkov Telescope

Abstract

We have measured the gamma-ray fluxes of the blazars Mrk 421 and Mrk 501 in the energy range between 50 and 350 GeV (1.2 to 8.3 x 10^25 Hz). The detector, called CELESTE, used first 40, then 53 heliostats of the former solar facility "Themis" in the French Pyrenees to collect Cherenkov light generated in atmospheric particle cascades. The signal from Mrk 421 is often strong. We compare its flux with previously published multi-wavelength studies and infer that we are straddling the high energy peak of the spectral energy distribution. The signal from Mrk 501 in 2000 was weak (3.4 sigma). We obtain an upper limit on the flux from 1ES 1426+428 of less than half that of the Crab flux near 100 GeV. The data analysis and understanding of systematic biases have improved compared to previous work, increasing the detector's sensitivity.

arXiv comment15 pages, 14 figures, accepted to A&A (July 2006) August 19 -- corrected error in author list

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• VHE Gamma-Ray Observation of the Crab Nebula and its Pulsar with the MAGIC telescope
• Fermi Large Area Telescope Observations of the Crab Pulsar and Nebula
• Very-high energy gamma-ray astronomy: A 23-year success story in high-energy astroparticle physics
• Observations of TeV gamma-rays from Mrk 421 during Dec. 2005 to Apr. 2006 with the TACTIC telescope
• Gamma-ray flare and absorption in Crab Nebula: Lovely TeV-PeV astrophysics
• Ground-based gamma-ray astronomy: history and development of techniques
• TeV Gamma-ray Observations of Markarian 421 using TACTIC during 2009-10
• Very high-energy observations of the two high-frequency peaked BL Lac objects 1ES 1218+304 and H 1426+428
• Search for TeV $\gamma$ -rays from H1426+428 during 2004-07 with the TACTIC telescope
• Very high energy observations of the BL Lac objects 3C 66A and OJ 287