tokens: on the impurity, physical structure, and the temperature of ice grains. In turn, we may be able to set constraints on the processes experienced by 2I and its formation conditions. There are three objectives of our study: (1) to search for diagnostic absorption features of water ice and other compounds (such as hydrated minerals or organic materials) in the coma or on its surface; (2) to compare water ice features in 2I to other Solar System icy objects (e.g., comets, Centaurs, and Kuiper Belt objects) and set constraints on its birth conditions; (3) to search for the ultra-red organic materials that may be present on the surface of 2I or in the coma as a result of long-term exposure to Galactic cosmic rays or UV bombardment. 2. Observations and data reduction We observed 2I on three separate occasions. The first two observations were made using director discretionary time allocations. The first observation was carried out in the morning twilight on 2019 September 19 UT using the SpeX spectrograph at the 3m IRTF telescope. The second observation was made on September 24 UT with the Gemini Near-InfraRed Spectrograph (GNIRS) spectrograph on the 8m GEMINI telescope. The last observation was made in service mode, again with the SpeX/IRTF, on October 9. The observing geometry is shown in Table 1 . Table 1. Journal of the 2I observations. Notes. (†) r h and Δ are the heliocentric and geocentric distances, respectively; (‡) α is the phase angle; (§) χ is the airmass. The SpeX observations were made with the high-throughput prism mode (0.8–2.5 μ m) and a 0.8′′ × 15′′ slit that provides a spectral resolving power of R ∼ 150 ( Rayner et al. 2003 ). The GNIRS observations were taken with the short camera (plate scale: 0.15′′ pix −1 ). The SXD cross-dispersed mode, 32 l mm −1 grating and 1.0′′ slit, provides an averaged resolving power of R ∼ 1700 over 0.9–2.5 μ m ( Elias et al. 2006 ). At least one nearby G-type star was observed together with the comet during each run, which was used both as the telluric correction standard star and the solar analog. The SpeX data were reduced using the reduction pipeline SpeXtool ( Cushing et al. 2004 ). The GNIRS data were reduced using the Image Reduction and Analysis Facility (IRAF) software and the Gemini IRAF package. Taking advantage of the similarity between the SpeX data and GNIRS data, we used the SpeXtool xtellcor routine for telluric correction and the xmergeorders routine for merging the GNIRS SXD spectra. 3. Results The NIR observations of 2I are presented in Fig. 1 . Although the three spectra were taken on different dates and with different instruments, they consistently appear featureless and show moderately red spectral slopes. We did not detect the diagnostic absorption bands of water ice at 1.5 and 2.0 μ m. Among the three NIR observations, the Gemini dataset has the highest signal-to-noise ratio (S/N). Thus, we use the Gemini spectra for further analysis. Fig. 1. Near-IR spectra of 2I/Borisov,
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