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D. Pascu, J.R. Rohde, P.K. Seidelmann (USNO), E.N. Wells, J.L. Hershey (CSC/STScI), B.H. Zellner (GaSou), A.D. Storrs (STScI), D.G. Currie (UMd), A.S. Bosh (Lowell)
In July of 1997 we obtained 39 HST images of Neptune and satellites in the BVI filters for photometric, as well as astrometric and dynamical studies. Our preliminary photometric reductions (Pascu et al. BAAS 30 1101, 1998) indicated leading/trailing brightness asymmetries for both Triton and Proteus, as well as a large color difference between the two moons. The color difference, in (B-V) and (V-I), implied an unusually blue color for Proteus, or a red color for Triton. However, HST/NICMOS observations indicate that Proteus is a red object (B.A. Smith 1998, Pers. Comm.), and Buratti et al. (BAAS 30 1107, 1998) report a reddening in Triton's spectrum in observations made in October, 1997. We have reanalyzed our observations, with results in substantial agreement with our earlier determinations. We are now left with the conclusion that we have observed an "episodic" reddening of Triton, of the type described by Buratti et al. (Icarus 110, 1994).