# # Program information file # PROGRAM_ID 2022B075 PROGRAM_TITLE Rotationally resolved spectroscopy of the dwarf planet [136199] Eris PROGRAM_INV1 Bryan Holler PROGRAM_INV2 Richard Cartwright PROGRAM_INV3 Jason Hofgartner PROGRAM_INV4 Leslie Young PROGRAM_INV5 Silvia Protopapa PROGRAM_SCICAT Centaurs / TNOs / KBOs PROGRAM_ABSTRACT_BEG The dwarf planet-class Kuiper Belt Object [KBO] Eris has a similar surface composition to Triton, Pluto, and Makemake, exhibiting strong methane absorption features in near-infrared spectra. We propose to obtain the first set of rotationally resolved spectra of Eris using SpeX in Prism mode in order to study the distribution of volatile ices across the surface and constrain Eris' rotation period. These observations would occur every other night over a 15-day period for 8 total nights in order to properly sample a full Eris rotation, which could be anywhere from ~14 hours to ~16 days. The exact rotation period has implications for the formation of Eris' satellite Dysnomia. PROGRAM_ABSTRACT_END