The Delivered Image Quality with the MOSAIC Cameras at the Kitt Peak 4 m Mayall and Cerro Tololo 4 m Blanco Telescopes.

We analyze several thousand archival images from the NOAO Science Archive obtained over a five year period (2006-2011) using the MOSAIC cameras on the Kitt Peak National Observatory 4 m Mayall and Cerro Tololo Inter-American Observatory 4 m Blanco telescopes in order to investigate the delivered image quality (DIQ). We fit the resulting point spread functions with Moffat functions and find that the profiles can be approximated by Moffat profiles with ß 3:5. We analyze the DIQ distributions and investigate their dependence on various observational, environmental, and temporal variables. We find that the DIQ of the MOSAIC cameras is similar at both sites. The Mayall data show no significant variation of DIQ with wavelength, but the Blanco data show a gradual rise of DIQ toward shorter wavelengths. The DIQ shows little variation with elevation for zenith distance <50° (airmass 1:6). The modal value of the DIQ distribution is larger for longer exposure time images, suggesting that improvements in the guiding, tracking, mirror support, and/or focus control may improve the DIQ. The DIQ also degrades when the mirror temperature deviates from the ambient temperature by more than 1°. Better thermal control of the mirror and focus will likely improve the DIQ. [ABSTRACT FROM AUTHOR]