Mariner 9 star photography.

Successful photography of stars by the Mariner 9 spacecraft has confirmed both mathematical prediction of point source response by vidicons and preflight calibration results. Camera-B limiting magnitude and integrated image data are presented to provide information relevant to absolute photometric reduction. These data appear consistent to better than 15% and suggest a good calibration source. Decalibration of Mars picture information, however, requires precise knowledge of Mars spectral radiance and camera point spread function. The effect of image motion on star detection thresholds is also discussed.