Temperature and aerosol structure of the nightside Uranian stratosphere from Voyager 2 photopolarimeter stellar occultation measurements

Voyager 2 UV-photopolarimeter occultation observations toward Gamma Peg, obtained on the nightside of Uranus at planetocentric latitude 68.9 deg N on January 24, 1986, are used to probe the structure of the Uranian atmosphere. The data are presented graphically and compared with the predictions of model atmospheres. The temperature profile for an aerosol-free atmosphere ranges from 85 + or - 2.3 K at 2.7 mbar to 96 + or - 13 K at 370 microbar, and the 1-mbar radius is found to be 25,219 + or - 6.3 km. The extinction coefficient for an aerosol haze layer at 1 mbar or higher is shown to be less than or equal to about 0.0001/km, but it is suggested that a well-mixed haze layer consisting of meteor or ring dust and/or photochemical condensates may well be present below 3 mbar.