As a calibrated laser pulse propagates through the atmosphere, the Rayleigh scattered light intensity arriving at the VERITAS telescopes can be calculated precisely when atmospheric conditions are good. This technique is originally developed for the absolute calibration of ultra high energy cosmic ray fluorescence telescopes but is also applicable to imaging atmospheric Cherenkov telescopes. In this paper, we present two nights of laser data taken at various distances away from the VERITAS telescopes in comparison to simulated Rayleigh scattering data.

VERITAS

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 3 (OG part 2), pages 1453-1456