Large-format infrared arrays are enablers for a variety of astronomical applications, from wide-field imaging to very high-resolution spectroscopy over a wide range of wavelength. We present the optimization of the science-grade H4RG array used in the SPIRou high-resolution spectrograph designed for high-precision velocity measurements. In SPIRou nominal science operation, the array is used in a relatively low flux regime, well below the full-well of the arrays and, for some applications, the readout noise is a major contributor to the overall signal-to-noise budget. We describe the detector fine-tuning process as well as the derived properties and their impact on performances. We identify persistence as potentially problematic under certain circumstances for infrared m/s velocimetry.
The Near Infrared Imager and Slitless Spectrograph (NIRISS) Optical Simulator (NOS) is a
laboratory simulation of the single-object slitless spectroscopy and aperture masking interferometry modes of the
NIRISS instrument onboard the James Webb Space Telescope (JWST). A transiting exoplanet can be simulated
by periodically eclipsing a small portion (1% - 10ppm) of a super continuum laser source (0.4 μm - 2.4 μm) with
a dichloromethane filled cell. Dichloromethane exhibits multiple absorption features in the near infrared domain
hence the net effect is analogous to the atmospheric absorption features of an exoplanet transiting in front of its
host star. The NOS uses an HAWAII-2RG and an ASIC controller cooled to cryogenic temperatures. A separate
photometric beacon provides a flux reference to monitor laser variations. The telescope jitter can be simulated
using a high-resolution motorized pinhole placed along the optical path. Laboratory transiting spectroscopy data
produced by the NOS will be used to refine analysis methods, characterize the noise due to the jitter, characterize
the noise floor and to develop better observation strategies. We report in this paper the first exoplanet transit
event simulated by the NOS. The performance is currently limited by relatively high thermal background in the
system and high frequency temporal variations of the continuum source.