IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2022B996 PROGRAM_TITLE Near-Sun Comet 96P/Machholz PROGRAM_INV1 Quanzhi Ye PROGRAM_INV2 PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG Our goal is to measure the size and albedo of the nucleus by constraining its thermal spectrum using near-simultaneous MIRSI imaging at 4.9 and 10.7 microns. IRTF's pointing restriction (minimum 20 degrees from the Sun) allows observation of 96P until 0.6 au from the Sun (or 2023 January 16 around 0 hours UT), thus our observation is best to be scheduled as close to 2023 January 15 as possible, but no earlier than 2023 January 11 (of which the comet would be more than 0.7 au from the Sun, and will thus be too faint for our purpose). Assuming a geometric albedo of 0.1 and a diameter of 6.4 km (Lamy et al. 2004, Comets II, 223), an heliocentric distance of 0.6 au translates to an isothermal blackbody temperature of 360 K, we estimate that it will take ~160 minutes of wall clock time (i.e. overhead included) at 4.9 micron and 20 minutes of wall clock time at 10.7 micron to achieve an S/N of 3-5, which adds up to a 3-hour program and would be suffice for our goal. PROGRAM_ABSTRACT_END