Catalog of Ultraviolet Bright Stars: Strategies for UV Occultation Measurements, Planetary Illumination Modeling, and Sky Map Analyses Using Hybrid IUE-Kurucz Spectra

Abstract

Ultraviolet spectroscopy is a powerful method to study planetary surface composition through reflectance measurements, atmospheric composition through stellar/solar occultations, transits of other planetary bodies, and direct imaging of airglow and auroral emissions. The next generation of ultraviolet spectrographs (UVS) on board ESA’s Jupiter Icy Moons Explorer and NASA’s Europa Clipper missions will perform such measurements of Jupiter and its moons in the early 2030s. This work presents a compilation of a detailed UV stellar catalog, named Catalog of Ultraviolet Bright Stars (CUBS), of targets with high intensity in the 50–210 nm wavelength range with applications relevant to planetary spectroscopy. These applications include (1) planning and simulating occultations, including calibration measurements; (2) modeling starlight illumination of dark, nightside planetary surfaces primarily lit by the sky; and (3) studying the origin of diffuse Galactic UV light as mapped by existing data sets from Juno-UVS and others. CUBS includes observations from the International Ultraviolet Explorer (IUE) and additional information from the SIMBAD database. We have constructed model spectra at 0.1 nm resolution for almost 90,000 targets using interpolated Kurucz models (which have a resolution of 1 nm) and, when available, IUE spectra. CUBS also includes robust checks for agreement between the Kurucz models and the IUE data. We also present a tool for which our catalog can be used to identify the best candidates for stellar occultation observations, with applications for any UV instrument. We report on our methods for producing CUBS and discuss plans for its implementation during ongoing and upcoming planetary missions.