# # Program information file # PROGRAM_ID 2023B038 PROGRAM_TITLE Occasional Triton spectra 2020-2023 for rotational and seasonal variability, with concurrent Neptune imaging. PROGRAM_INV1 Leslie Young PROGRAM_INV2 William Grundy PROGRAM_INV3 Bryan Holler PROGRAM_INV4 Glenn Orton PROGRAM_INV5 Michael Roman PROGRAM_SCICAT major planets / satellites PROGRAM_ABSTRACT_BEG We propose observations of Triton's 0.7-2.55 micron spectrum with IRTF/SpeX in SXD mode, to study the short and long-term variability of Triton's surface ices, to study their composition, temperature, mixing state, and grain size. This extends a long-running program that includes baseline campaigns that sample Triton's rotational variation approximately every five years with occasional runs in the intervening semesters. This proposal is for occasional runs, since a successful baseline run was completed in 2019B. It will soon be the end of Triton's southern summer, with sub-solar latitudes ranging from -37 deg in July 2020 to -33 deg in Nov 2023. Continued spectra can be used to [i] detect transient anomolies, if any, [ii] decouple migration from viewing geometry, and [iii] search for new ices at newly exposed latitudes. The observation strategy will closely mirror that of Grundy and Young 2004 [Icarus 172, 455-465], Grundy et al. 2010 [Icarus 205, 594-604], and Holler et al. 2016 [Icarus 267, 255-266]. Concurrent imaging of Neptune will further characterize the planet's changeable clouds over time, better testing theories of sub-seasonal trends in cloud coverage [Roman et al, 2022, PSJ 3, 78]. PROGRAM_ABSTRACT_END