ASTRONIRCAM—the infrared camera-spectrograph for the 2.5-m telescope of SAI Caucasian observatory

ASTRONIRCAM is a cryogenic-cooled slit camera-spectrograph for the spectral range 1–2.5 μm installed at the Nasmyth focus of the 2.5-meter telescope of the Caucasian observatory of the Sternberg Astronomical Institute of Lomonosov Moscow State University. The instrument is equipped with a HAWAII-2RG 2048×2048 HgCdTe array. Grisms are used as dispersive elements. In the photometric mode ASTRONIRCAM allows for extended astronomical object imaging in a 4.′6 × 4.′6 field of view with a 0.269 arcsec/pixel scale in standard photometric bands J, H, K, and K s as well as in the narrow-band filters centered on the lines CH4, [Fe II], H2 v=1-0 S(1), Br γ , and CO. In the spectroscopic mode, ASTRONIRCAM takes spectra of extended or point-like sources with a spectral resolution of R = λ/Δλ ≤ 1200. The general design, optical system, detector electronics and readout, amplification and digitization schemes are considered. The GAIN conversion factor measurement results are described as well as its dependence on the accumulated signal (nonlinearity).