Multicolor Photometry of the Uranus Irregular Satellites Sycorax and Caliban

Abstract

We report on accurate BVRI photometry for the two Uranian irregular satellites Sycorax and Caliban. We derive colors showing that Sycorax is bluer than Caliban. Our data allow us to detect a significant variability in Caliban's light curve, which suggests an estimated period of about 3 hr. Although it is the brighter of the two bodies, Sycorax does not display a strong, statistically significant variability. However, our data seem to suggest a period of about 4 hr.