The widest contiguous field of view at Dome C and Mount Graham

The image quality from Ground-Layer Adaptive Optics (GLAO) can be gradually increased with decreased contiguous field of view. This trade-off is dependent on the vertical profile of the optical turbulence (Cn2 profiles). It is known that the accuracy of the vertical distribution measured by existing Cn2 profiling techniques is currently quite uncertain for wide field performance predictions 4 to 20 arcminutes. With assumed uncertainties in measurements from Generalized-SCIDAR (GS), SODAR plus MASS we quantify the impact of this uncertainty on the trade-off between field of view and image quality for photometry of science targets at the resolution limit. We use a point spread function (PSF) model defined analytically in the spatial frequency domain to compute the relevant photometry figure of merit at infrared wavelengths. Statistics of this PSF analysis on a database of Cn2 measurements are presented for Mt. Graham, Arizona and Dome C, Antarctica. This research is part of the activities of ForOT (3D Forecasting of Optical Turbulence above astronomical sites).