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We analyze an extensive data set of immersion and emersion lightcurves of theoccultation of 28 Sgr by Saturn's atmosphere on 3 July 1989. The data give profilesof number density as a function of altitude at a variety of latitudes, at pressuresranging from about 0.5 to about 20 [micro]bar. The atmosphere is essentiallyisothermal in this range, with a temperature close to 140 K for an assumed meanmolecular weight of 2.135. Owing to favorable ring geometry, an accurate radialscale is available of all observations, and we confirm the substantial equatorialbulge produced by zonal winds of [approximately]450 m/s first observed in theVoyager radio-occultation experiments. The fact that the bulge is still presentat microbar pressures suggests that the equatorial winds persist to high altitudes.According to our radial scale, the 2.4-[micro]bar level, which corresponds tohalf-flux in the stellar occultations, is at an equatorial radius of 60,960 km.This radial scale is in good agreement with the Voyager radio-occultation data atmbar pressures and allows smooth interpolation of the isothermal structure betweenthe stellar-occultation and radiooccultation regions. We do not have such a smoothinterpolation between our data and Voyager ultraviolet occultation data, unlesswe discard the lowest 200 km of Voyager ultraviolet data. When this is done, weobtain a complete atmospheric model from an equatorial radius of 61,500 km down to an equatorial radius of 60,500 km. This model gives excellent agreement betweenall 28 Sgr, Voyager, and Pioneer 11 data. Key Words: occultations; Saturn, atmosphere; Saturn.

Saturn's pole, as defined by the ring plane, can be determined by the geometry of the 3 July 1989 occultation of 28 Sgr by Saturn. High precision timing of 12 circular edges in the C-ring with radius from 84750 to 90615 kilometers, Cassini division's three features, Encke gap's edges and the Keeler gap's outer edges were used to define Saturn's pole by the ring plane. The observations were made from one station in the southern hemisphere, and five stations in the northern hemisphere. This provided a terrestrial chord separation of 10,000 km. The radio and stellar-occultation data of the ring radii obtained from Voyager is used to solve the position angle and opening angle of the apparent ring ellipses.