# # Program information file # PROGRAM_ID 2022A052 PROGRAM_TITLE A Study of Parent Volatile Compositions and Searching for Seasonal Effects in Short-period Comet 19P/Borrelly. PROGRAM_INV1 Mohammad Saki PROGRAM_INV2 Erika Gibb PROGRAM_INV3 Michael DiSanti PROGRAM_INV4 Neil Dello Russo PROGRAM_INV5 Ronald Vervack PROGRAM_SCICAT comets PROGRAM_ABSTRACT_BEG We propose to use iSHELL at NASA-IRTF to measure near- and post-perihelion composition of coma gases [H2O, OH, CO, CH3OH, C2H6, CH4, HCN, and NH3] released from ices in the nucleus of Jupiter-family comet [JFC] 19P/Borrelly. We emphasize three equally important goals: [1] JFCs as an under-represented group in taxonomic studies of parent volatiles, [2] determine abundances of hypervolatiles CO and CH4, the most volatile species systematically measured in comets, and [3] Testing seasonal effects and asymmetry about perihelion. 19P offers an opportunity to measure parent volatile abundances and test for compositional variability due to seasonal effects over a time span of ~1 month during a single apparition. The Doppler shift of ~12.4 km/s in late February is sufficient for shifting cometary emissions [particularly for CO and CH4] out of their telluric counterparts, allowing us to detect or put stringent upper limits on both species. We will use three iSHELL settings: Lcustom samples H2O, HCN, and NH3; Lp1 samples CH4, C2H6, CH3OH and OH [OH prompt emission, a tracer for the production and spatial distribution of H2O]; and M2 samples H2O and CO. Owing to poor observing geometry in its previous apparitions, 2022 perihelion passage of 19P is the first [and an excellent] opportunity for these measurements since its 2001 apparition. Owing to its high resolving power, spectral coverage, flexible scheduling for serial observation, and superior M-band guiding, these studies can only be done with iSHELL at NASA-IRTF. PROGRAM_ABSTRACT_END