IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2022B034 PROGRAM_TITLE The Moon's three micron band: Behavior during partial and total eclipse PROGRAM_INV1 Paul Lucey PROGRAM_INV2 Casey Honniball PROGRAM_INV3 Abigail Flom PROGRAM_INV4 Chiara Ferrari-Wong PROGRAM_INV5 PROGRAM_SCICAT major planets / satellites PROGRAM_ABSTRACT_BEG The project will observe the lunar surface in the near-IR at 3 microns during partial and total lunar eclipse to understand the abundance and distribution of water on the Moon. At the Moon's 1 AU from the Sun, the 3um region is a mixture of solar reflected and lunar emitted flux, necessitating thermal correction to obtain a true 3 micron band depth to determine water abundances. However, competing models arrive at diametrically opposed results regarding three micron behavior with location, temperature and lunar time of day. One model shows the 3 micron band does not vary in any parameter; others show widely varying latitude, temperature behavior. However, during partial eclipse lunar temperature drop to the extent that 3um reflectance band depths can be obtained without thermal correction. In total eclipse, lunar water features should manifest as emission features at 3um for high thermal inertia locations known from nighttime IR measurements, uncompromised by solar reflected flux. Thus these observations are a unique perspective of water on the Moon. Both types of observations have been successfully carried out during previous eclipses so observing strategies are established. The eclipse of November 2022 is the last eclipse favorably situated for observations from Hawaii for many years, so this observing run will close out the program. PROGRAM_ABSTRACT_END