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# Program information file
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PROGRAM_ID           2024B096
PROGRAM_TITLE        SpeX observations of 13P/Olbers and C/2023 A3 [Tsuchinshan-ATLAS]: Exploring the overall coma composition of comets
PROGRAM_INV1         Ron Vervack
PROGRAM_INV2         Neil Dello Russo
PROGRAM_INV3         Boncho Bonev
PROGRAM_INV4         Michael DiSanti
PROGRAM_INV5         Erika Gibb
PROGRAM_SCICAT       comets
PROGRAM_ABSTRACT_BEG
Semester 2024B represents an opportunity to sample comets from two dynamical families: Halley-family comet [HFC] 13P/Olbers and Oort cloud comet [OCC] C/2023 A3 [Tsuchinshan-ATLAS]. Our proposed study emphasizes three science objectives for which IRTF/SpeX is ideal: [1] sample overall gas emission by observing strong but overlapping emissions between 2.8 and 4.2 um, [2] sample the continuum from 0.7 to 4.2 um to investigate the dust environment, and [3] build a database of moderate-resolution comet spectra. Owing to its large spectral grasp, SpeX enables a survey of the overall 'organics' region between 3.2-3.6 um simultaneously with other gas emissions [e.g., H2O]. Simultaneous measurements of the underlying continuum provide information on cometary dust grains and ice signatures, both of which are important in understanding formation conditions in the solar nebula. Because the resolution and wavelength grasp of JWST/NIRSpec and most near-IR spacecraft instruments are comparable to [or less than] those of SpeX, a long-term database of SpeX comet observations will aid in analyses and interpretation of such data, thereby addressing IRTF's role in supporting NASA missions. Specific reasons for targeting these comets: 12P is an HFC, periodic comets with longer periods than JFCs and rarely observable in good apparitions; as a 'fresh' OCC C/2023 A3 allows comparisons to more-processed periodic comets to understand evolutionary changes. C/2023 A3 is also predicted to be the best comet in 30 years, enabling unprecedented observations as a function of heliocentric distance. To achieve our objectives, we use the SpeX LXD-short and SXD settings. Guidedog is sufficient for guiding; MORIS is not needed. The 0.8 arcsec slit is used for 13P, the 0.3 arcsec slit for A3 owing to its exceptional brightness. Our request includes four runs [one for 13P post-perihelion, three to sample C/2023 A3 across a range of heliocentric distance] for a total of 24 hours.
PROGRAM_ABSTRACT_END