The Ultraviolet Spectrum of Triton from HST: First Results

Abstract

We report on the first Hubble Space Telescope (HST) spectra of Neptune's largest satellite, Triton. The spectra were taken on 16-17 May 1992 by the HST Faint Object Spectrograph. They span the region 2220-3278 Å. This overlaps IUE spectra of Triton we obtained, 2700-3100 Å, and penetrates the region from 2220 to 2550 A for the first time. The derived 2800-Å albedo confirms IUE results made in 1988 and 1989 at nearly the same orbital phase. Among the findings reached in this first analysis of HST Triton spectra is that the higher S/N of the HST data relative to previous IUE results reveals, for the first time, that Triton's UV reflectivity slope flattens and is no longer red below ∼2850 Å.