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We present the Keck Infrared Transient Survey, a NASA Key Strategic Mission Support program to obtain near-infrared (NIR) spectra of astrophysical transients of all types, and its first data release, consisting of 105 NIR spectra of 50 transients. Such a data set is essential as we enter a new era of IR astronomy with the James Webb Space Telescope (JWST) and the upcoming Nancy Grace Roman Space Telescope (Roman). NIR spectral templates will be essential to search JWST images for stellar explosions of the first stars and to plan an effective Roman SN Ia cosmology survey, both key science objectives for mission success. Between 2022 February and 2023 July, we systematically obtained 274 NIR spectra of 146 astronomical transients, representing a significant increase in the number of available NIR spectra in the literature. Here, we describe the first release of data from the 2022A semester. We systematically observed three samples: a flux-limited sample that includes all transients <17 mag in a red optical band (usually ZTF ror ATLAS obands); a volume-limited sample including all transients within redshift z< 0.01 (D≈ 50 Mpc); and an SN Ia sample targeting objects at phases and light-curve parameters that had scant existing NIR data in the literature. The flux-limited sample is 39% complete (60% excluding SNe Ia), while the volume-limited sample is 54% complete and is 79% complete to z= 0.005. Transient classes observed include common Type Ia and core-collapse supernovae, tidal disruption events, luminous red novae, and the newly categorized hydrogen-free/helium-poor interacting Type Icn supernovae. We describe our observing procedures and data reduction using PypeIt, which requires minimal human interaction to ensure reproducibility.

CorMASS (Cornell Massachusetts Slit Spectrograph) is a compact, low-resolution (R?300), double-pass prism cross-dispersed near-infrared (NIR) spectrograph in operation on the Palomar Observatory 60 inch telescope. Its two-dimensional spectral format provides simultaneous coverage of ??0.75 ?m to ??2.5 ?m (zJHKbands). A remotely operated cold flip mirror permits its NICMOS3 detector to function as a Ksslit viewer to assist object placement into the 2''× 15''slit. CorMASS was primarily designed for the rapid spectral classification of low-mass stellar and substellar objects identified by the Two-Micron All Sky Survey (2MASS). The efficiency and resolution of CorMASS also make it a versatile instrument for the spectral observation and classification of many other types of bright objects (K<14) including quasars, novae, and emission-line objects.

This paper describes the design, expectations, and prototyping of a new allsky survey, called 2MASS (Two Micron All Sky Survey) to be carried out with the new generation of infrared array detectors.

We report 1.25-18.5 ?m infrared (IR) photometric measurements acquired during an 850 day period following outburst of the ONeMg "neon nova" V1974 Cygni (Nova Cygni 1992). The decline rates of the 0.55 V, 1.25 J, 1.6 H, and 2.3 ?m Klight curves all showed an abrupt transition from a t-3/2slope to a t-3slope at ?170 days after outburst. The 3.5 ?m (L) light curve exhibited a steady t-3/2decline rate from days 10 to ? 600, and the 4.5 ?m (M) intensity maintained a t-3/2decline rate until the last observation on day ? 250. Examination of criteria for identifying CO and ONeMg novae from their near-IR light curves shows that while V1974 Cyg is identifiable as an ONeMg nova, it is a much less extreme case than QU Vul. We propose that the break in the slope of the 0.55-2.3 ?m light curves is produced by a change in excitation conditions within a freely expanding optically thin shell that causes the cooling to shift rather abruptly from hydrogen recombination lines to near-IR coronal emission lines of highly ionized metals. The behavior of the visible light and IR light curves provides no evidence for dust formation in the ejecta of V1974 Cyg during the first ? 240 days following the outburst. We derive a value for the mass of gas in the ejecta of Mgas? 2-5 × 10-4M?.

We describe the design and performance of the near-infrared (1.51-1.70 ?m), fiber-fed, multi-object (300 fibers), high resolution (R= ?/??? 22,500) spectrograph built for the Apache Point Observatory Galactic Evolution Experiment (APOGEE). APOGEE is a survey of ?105red giant stars that systematically sampled all Milky Way populations (bulge, disk, and halo) to study the Galaxy's chemical and kinematical history. It was part of the Sloan Digital Sky Survey III (SDSS-III) from 2011 to 2014 using the 2.5 m Sloan Foundation Telescope at Apache Point Observatory, New Mexico. The APOGEE-2 survey is now using the spectrograph as part of SDSS-IV, as well as a second spectrograph, a close copy of the first, operating at the 2.5 m du Pont Telescope at Las Campanas Observatory in Chile. Although several fiber-fed, multi-object, high resolution spectrographs have been built for visual wavelength spectroscopy, the APOGEE spectrograph is one of the first such instruments built for observations in the near-infrared. The instrument's successful development was enabled by several key innovations, including a "gang connector" to allow simultaneous connections of 300 fibers; hermetically sealed feedthroughs to allow fibers to pass through the cryostat wall continuously; the first cryogenically deployed mosaic volume phase holographic grating; and a large refractive camera that includes mono-crystalline silicon and fused silica elements with diameters as large as ?400 mm. This paper contains a comprehensive description of all aspects of the instrument including the fiber system, optics and opto-mechanics, detector arrays, mechanics and cryogenics, instrument control, calibration system, optical performance and stability, lessons learned, and design changes for the second instrument.