Calibrations for high precision differential astrometry onboard Theia and HWO
Abstract
Future space astrometry missions such as Theia and an astrometric mode of the Habitable Worlds Observatory (HWO) require detector calibration and instrumental characterization at an unprecedented level to achieve sub-micro-arcsecond precision. This work presents three complementary developments addressing these requirements. First, we report an independent characterization of the GIGAPYX-4600 back-side illuminated CMOS detector, evaluating its linearity, readout noise, dark current, pixel response non-uniformity, defective pixel fraction, and inter-pixel capacitance. The results demonstrate excellent detector performance and confirm its suitability as a candidate for future gigapixel focal planes. Second, we develop an interferometric calibration method based on Young's fringes to measure pixel centroid displacements, enabling the characterization of inter-pixel response variations with an approach compatible with onboard implementation. The method is investigated through numerical simulations and an experimental testbed using the GIGAPYX-4600 detector. Finally, we introduce an astro-calibration framework that jointly estimates stellar astrometric parameters, telescope attitude, plate scale, and optical distortion through a global iterative optimization. Although this calibration approach is still under development, simulations and laboratory activities are underway to validate its performance. Together, these developments contribute to the technological and calibration framework required for the next generation of high-precision astrometric space missions.
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BibTeX
@misc{lizzana2026calibrations,
title = {{Calibrations for high precision differential astrometry onboard Theia and HWO}},
author = {Manon Lizzana and Fabien Malbet and Hugo Rousset and Sébastien Soler and Fabrice Pancher and Éric Thiébaut},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.15615},
eprint = {2609.15615},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.15615},
}
RIS
TY - UNPB
TI - Calibrations for high precision differential astrometry onboard Theia and HWO
AU - Manon Lizzana
AU - Fabien Malbet
AU - Hugo Rousset
AU - S{é}bastien Soler
AU - Fabrice Pancher
AU - {É}ric Thi{é}baut
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.15615
UR - https://arxiv.org/abs/2609.15615
AB - Future space astrometry missions such as Theia and an astrometric mode of the Habitable Worlds Observatory (HWO) require detector calibration and instrumental characterization at an unprecedented level to achieve sub-micro-arcsecond precision. This work presents three complementary developments addressing these requirements. First, we report an independent characterization of the GIGAPYX-4600 back-side illuminated CMOS detector, evaluating its linearity, readout noise, dark current, pixel response non-uniformity, defective pixel fraction, and inter-pixel capacitance. The results demonstrate excellent detector performance and confirm its suitability as a candidate for future gigapixel focal planes. Second, we develop an interferometric calibration method based on Young's fringes to measure pixel centroid displacements, enabling the characterization of inter-pixel response variations with an approach compatible with onboard implementation. The method is investigated through numerical simulations and an experimental testbed using the GIGAPYX-4600 detector. Finally, we introduce an astro-calibration framework that jointly estimates stellar astrometric parameters, telescope attitude, plate scale, and optical distortion through a global iterative optimization. Although this calibration approach is still under development, simulations and laboratory activities are underway to validate its performance. Together, these developments contribute to the technological and calibration framework required for the next generation of high-precision astrometric space missions.
ER -