Voyager observations of Nereid

We have analyzed observations of Nereid obtained by Voyager 2 over a 12-day interval at solar phase angles of 25°-96° to determine the satellite's size and basic phtometric properties. Nereid's radius is found to be 170+/-25 km: its geometric albedo (λ=0.48 μ) exceeds 0.16 and is probably close to 0.2. There is no evidence of rotation light curve in the Voyager observations, any light curve amplitude being definitely less than 0.15 magnitude (mag) (total amplitude). Hapke's photometric model, applied to combination of the Voyager and Earth-based data taken at opposition, yields a geometric albedo of about 0.2, a phase intergral of 0.5, and a Bond albedo of 0.1. In terms of albedo, color, and photometric properties, Nereid is similar to some of the icy satellites of Uranus but is quite distinct from the group of six small inner satellites of Neptune discovered by Voyager. Although these satellites share Nereid's neutral color, they are much darker (albedos 6% versus 20%) and have much higher phase coefficients (0.035 versus 0.024 mag/deg). We conclude that Nereid is unlike these ``carbonaceous'' objects and is probably a ``dirty'' icy body. The satellite's spin state (period and spin axis direction) cannot be determined from the Voyager data.