The latest generation of high-resolution spectrograph instruments on 10m-class telescopes continue to pursue challenging science cases. Consequently, ever more precise calibration methods are necessary to enable trail-blazing science methodology. We present the High-resolution Infrared SPectrograph for Exoplanet Characterization (HISPEC) Calibration Unit (CAL), designed to facilitate challenging science cases such as Doppler imaging of exoplanet atmospheres, precision radial velocity, and high-contrast high-resolution spectroscopy of nearby exoplanets. CAL builds upon the heritage from the pathfinder instrument Keck Planet Imager and Characterizer (KPIC) and utilizes four near-infrared (NIR) light sources encoded with wavelength information that are coupled into single-mode fibers. They can be used synchronously during science observations or asynchronously during daytime calibrations. A hollow cathode lamp (HCL) and a series of gas absorption cells provide absolute calibration from 0.98 {\mu}m to 2.5 {\mu}m. A laser frequency comb (LFC) provides stable, time-independent wavelength information during observation and CAL implements a lower finesse astro-etalon as a backup for the LFC. Design lessons from instrumentation like HISPEC will serve to inform the requirements for similar instruments for the ELTs in the future.
@article{arxiv.2311.10239,
title = {Calibration Unit Design for High-Resolution Infrared Spectrograph for Exoplanet Characterization (HISPEC)},
author = {Ben Sappey and Quinn Konopacky and Nemanja Jovanovic and Ashley Baker and Jerome Maire and Samuel Halverson and Dimitri Mawet and Jean-Baptiste Ruffio and Rob Bertz and Michael Fitzgerald and Charles Beichman and Garreth Ruane and Marc Kassis and Chris Johnson and Ken Magnone and HISPEC Team},
journal= {arXiv preprint arXiv:2311.10239},
year = {2023}
}