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The CERES Field of View (FOV) is synonymous with the term Footprint and is determined by the Point Spread Function (PSF) which is a two-dimensional, bell-shaped function that defines the CERES instrument response to the viewed radiation field. The resolution of the CERES radiometers is usually referenced to the optical FOV which is 1.3° in the along-track direction and 2.6° in the cross-track direction. The CERES FOV or footprint size is referenced to an oval area that represents approximately 95% of the PSF response. Since the PSF is defined in angular space at the instrument, the CERES FOV is a constant in angular space, but grows in surface area from a minimum at nadir to a larger area at shallow viewing angles.