  This paper provides a comprehensive overview of the subsystems of the NIGHT
instrument. NIGHT (the Near Infrared Gatherer of Helium Transits) is a
narrowband, high-resolution spectrograph, marking the first dedicated survey
instrument for exoplanetary atmosphere observations. Developed through a
collaboration between the Observatory of Geneva and the Universite de Montreal,
NIGHT aims to conduct an extensive statistical survey of helium atmospheres
around 100+ exoplanets over several years. The instrument will report new
detections of helium in exoplanet atmospheres and perform temporal monitoring
of a subset of these.
  NIGHT measures absorption from the metastable helium state during exoplanet
transits, observable in a triplet of lines around 1083nm. The instrument
comprises a vacuum enclosure housing the spectrograph, a front end unit for
fiber injection at the telescope's focal plane, and a calibration and control
rack containing calibration light sources and control hardware.
  The spectrograph is optimized for efficiency, achieving a uniform throughput
of approximately 71%. The primary disperser employs a VPH grating in a unique
double-pass configuration, enabling a spectral resolution of 75,000 while
maintaining high throughput. The detector is a HAWAII-1 infrared array, cooled
to 85K, with the spectrograph operating at room temperature. Thanks to its
relatively high throughput, NIGHT on a 2m class telescope is predicted to be as
sensitive as existing instruments on 4m class telescopes.
  The front end unit injects starlight and sky background into two separate
fibers leading to the spectrograph. It also performs near-infrared guiding and
includes a mechanism for injecting calibration light.
  The assembly and optical alignment of NIGHT's spectrograph and front end unit
are scheduled for July to September 2024, with the first light anticipated
before early 2025.
