First Visible Wavelength Lightcurves for the Northern Hemispheres of Titania and Oberon

Abstract

The most recently published lightcurves of the large Uranian satellites were published in 1989 and there have been no published lightcurves of the satellites’ northern hemispheres. In this work, I present the first visible-wavelength lightcurves of the northern hemispheres of Titania and Oberon. Observations of the Uranian satellites are inherently difficult given their proximity to Uranus. Contamination from stray Uranian light is a major challenge and the background near the satellites must be well characterized. I mitigated the effects of stray Uranian light using point spread function photometry. I modelled Uranus with a Lorentzian with the same full width at half max as the stellar point spread function. I also determined that Uranus’s profile is poorly modeled with a Gaussian or with the stellar empirical point spread function. After accounting for Uranian light in this way, there remains significant correlation between the photometric measurements of Titania and Oberon. I considered what may be causing this correlation and suggest several paths forward.