Photographic Positions of Saturn

Positional observations of Saturn are obtained with two photographic techniques and over 200 exposures of Saturn and its satellites taken between 1974 and 1980 with the USNO 26-in. refractor. The first method derives the center of Saturn's image from measurements of its rings. The second method indirectly derives the center from measurements of Saturn's satellites. The observations are compared to the Jet Propulsion Laboratory ephemeris of Saturn, DE 125 (Standish, 1985) to determine the external error of the observations. It is found that the external error in right ascensions is + or - 0.2 arcsec, while the declination error is + or - 0.27 arcsec.