Generalized SCIDAR Measurements at Mount Graham

Abstract

We present the results of optical turbulence measurements conducted with a Generalized SCIDAR (scintillation detection and ranging) at Mount Graham during 16 nights in 2004 and 2005 at the Vatican Advanced Technology Telescope. The principle of the data reduction process is shown, as is the validation of the obtained results. From the measured C N2 and wind speed profiles, the astroclimatic parameters, such as seeing ε 0, isoplanatic angle script V sign 0, wave-front coherence time τ 0, and isopistonic angle script V sign P, are calculated, and their seasonal variation is studied. With subtraction of the dome seeing, we obtained median values for ε 0 (0.67′), script V sign 0 (2.7′), τ 0 (3.6 ms), and script V sign P (3.3′) that indicate that the astronomical seeing at Mount Graham is comparable to the best sites in the world. The seasonal variation of the vertical structure of the C N2 profiles is studied, and the contribution by the ground-layer turbulence is analyzed. Furthermore, typical discretized C N2 profiles that are suitable for numerical simulations are determined. © 2007. The Astronomical Society of the Pacific. All rights reserved.