Processing photometric full-disk solar images

Daily, photometric. full-disk digital solar images have been taken at the San Fernando Observatory (SFO) at two resolutions and in several wavelengths for mon than eleven years. We describe the standard data processing techniques used for these images, including: calibration, limb fitting geometric correction, and production of a solar contrast map by limb-darkening removal. The resulting contrast maps have a photometric accuracy which is often a few tenths of a percent. We show that the geometric accuracy of our images, as measured by the reproducibility of disk and sunspot areas, is very high as well. The techniques described in this paper should be applicable to any instrument producing full-disk photometric images.