On-sky performance and prospects of near-infrared CMOS detectors in exoplanet detection: first year of SPIRIT
Abstract
Ultracool dwarfs are promising targets for detecting and characterising temperate terrestrial exoplanets. Their flux peaks in the near-infrared, beyond the wavelength cut-off of the silicon-based CCDs used by ground-based surveys dedicated to observing them, such as SPECULOOS. We present the on-sky performance of SPIRIT (SPeculoos InfraRed Imager for Transits), an InGaAs CMOS detector on the Callisto telescope at the SPECULOOS Southern Observatory, during its first year of operation, from mid-2022 to 2023. We use 328 visits of 73 targets to optimise our CMOS-specific reduction process, including our approach to glow effects and bad-pixel handling. We find the measured precision to be consistent with our theoretical noise model, achieving sub-part-per-thousand precision under good observing conditions across targets spanning J-band magnitudes of 10--13. We further illustrate SPIRIT's capabilities with two case studies: a simultaneous SPIRIT zYJ and CCD I + z observation of a TRAPPIST-1\,h transit, and monitoring observations of the fast-rotating dwarf LP~944-20. Our results confirm that InGaAs infrared CMOS detectors are a cost-effective and competitive technology for ground-based transit photometry of cool stars, and that they show promising prospects to become a core part of the next generation of instruments.
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BibTeX
@misc{janomunoz2026onsky,
title = {{On-sky performance and prospects of near-infrared CMOS detectors in exoplanet detection: first year of SPIRIT}},
author = {Clàudia Janó-Muñoz and Matthew J. Hooton and Peter P. Pedersen and Didier Queloz and Khalid Barkaoui and Yasmin T. Davis and Michaël Gillon and Benjamin V. Rackham and Mathilde Timmermans and Amaury H. M. J. Triaud and Sebastián Zúñiga-Fernández},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.19902},
eprint = {2610.19902},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.19902},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - On-sky performance and prospects of near-infrared CMOS detectors in exoplanet detection: first year of SPIRIT
AU - Clàudia Janó-Muñoz
AU - Matthew J. Hooton
AU - Peter P. Pedersen
AU - Didier Queloz
AU - Khalid Barkaoui
AU - Yasmin T. Davis
AU - Michaël Gillon
AU - Benjamin V. Rackham
AU - Mathilde Timmermans
AU - Amaury H. M. J. Triaud
AU - Sebastián Zúñiga-Fernández
PY - 2026
DA - 2026/10/14
PB - arXiv
DO - 10.48550/arxiv.2610.19902
UR - https://arxiv.org/abs/2610.19902
AB - Ultracool dwarfs are promising targets for detecting and characterising temperate terrestrial exoplanets. Their flux peaks in the near-infrared, beyond the wavelength cut-off of the silicon-based CCDs used by ground-based surveys dedicated to observing them, such as SPECULOOS. We present the on-sky performance of SPIRIT (SPeculoos InfraRed Imager for Transits), an InGaAs CMOS detector on the Callisto telescope at the SPECULOOS Southern Observatory, during its first year of operation, from mid-2022 to 2023. We use 328 visits of 73 targets to optimise our CMOS-specific reduction process, including our approach to glow effects and bad-pixel handling. We find the measured precision to be consistent with our theoretical noise model, achieving sub-part-per-thousand precision under good observing conditions across targets spanning J-band magnitudes of 10--13. We further illustrate SPIRIT's capabilities with two case studies: a simultaneous SPIRIT zYJ and CCD I + z observation of a TRAPPIST-1\,h transit, and monitoring observations of the fast-rotating dwarf LP~944-20. Our results confirm that InGaAs infrared CMOS detectors are a cost-effective and competitive technology for ground-based transit photometry of cool stars, and that they show promising prospects to become a core part of the next generation of instruments.
ER -