# Point spread function modelling for astronomical telescopes: a review focused on weak gravitational lensing studies

**Authors:** Tobias Liaudat, Jean-Luc Starck, Martin Kilbinger, Pierre-Antoine Frugier  
**arXiv:** [2306.07996](https://arxiv.org/abs/2306.07996)  
**Date:** 2023-06-12  
**Summary page:** https://www.summarizepaper.com/en/paper/2306.07996v1/

## Key points

- Accurate modelling of the Point Spread Function (PSF) is important in astronomical observations for measuring celestial objects' properties
- Upcoming galaxy surveys like Euclid and LSST will require novel PSF modelling techniques that can cope with tightening error requirements
- The authors introduce the optical background required for a more physically-motivated PSF modelling and propose an observational model that can be reused for future developments
- Different physical contributors to the PSF are discussed, including optic- and detector-level contributors and atmospheric effects
- Different methods for PSF modelling from parametric and non-parametric families for ground- and space-based telescopes are discussed, with their advantages and limitations
- Validation methods for PSF models are addressed, with several metrics related to weak lensing studies discussed in detail
- Current challenges in PSF modelling for astronomical telescopes include building fast yet powerful models that can meet higher PSF requirements set by next-generation telescopes such as Vera C. Rubin observatory, Euclid, and Roman space telescopes.
- Possible solutions suggested include exploiting parallel computing architectures or better-performing programming languages to address computing time being a common bottleneck for these models.
- Another challenge is incorporating complex effects into the PSF model that cannot be directly constrained from observations; simulations or complementary observations may be used to obtain this information but it may not match precisely with real observations due to changes in the telescope or measurement errors.
- Validation of PSF models from real observations is also challenging since access to ground truth PSFs is unavailable; current error propagation methods have simplifying assumptions that do not hold anymore with recent and upcoming telescopes so further development is required to define realistic requirements.
- The authors declare no conflict of interest and acknowledge funding from the TITAN ERA Chair project within the Horizon Europe Framework Program of the European Commission.
- Several open-source simulating and modelling software used in this review are listed, including GALSIM, WEBBPSF, PHOSIM, WAVEDIFF, SHAPEPIPE, PIFF, MCCD, RCA, PSFEX TINY-TIM ,and PHOTUTILS.
- Overall, this review provides a comprehensive overview of PSF modelling for astronomical telescopes with insights into current challenges, future directions and potential solutions.

## Summary

This review article focuses on the importance of accurate modelling of the Point Spread Function (PSF) in astronomical observations, particularly for measuring celestial objects' properties. With the increasing power and complexity of astronomical telescopes and instruments, upcoming galaxy surveys like Euclid and LSST will observe an unprecedented amount and quality of data, requiring novel PSF modelling techniques that can cope with tightening error requirements. The authors first introduce the optical background required for a more physically-motivated PSF modelling and propose an observational model that can be reused for future developments. They provide an overview of the different physical contributors to the PSF, including optic- and detector-level contributors and atmospheric effects. The authors then discuss different methods for PSF modelling from parametric and non-parametric families for ground- and space-based telescopes, with their advantages and limitations. Validation methods for PSF models are also addressed, with several metrics related to weak lensing studies discussed in detail. The review highlights current challenges in PSF modelling for astronomical telescopes, including building fast yet powerful models that can meet higher PSF requirements set by next-generation telescopes such as Vera C. Rubin observatory, Euclid, and Roman space telescopes. The authors suggest possible solutions such as exploiting parallel computing architectures or better-performing programming languages to address computing time being a common bottleneck for these models. Another challenge is incorporating complex effects into the PSF model that cannot be directly constrained from observations; simulations or complementary observations may be used to obtain this information but it may not match precisely with real observations due to changes in the telescope or measurement errors. Validation of PSF models from real observations is also challenging since access to ground truth PSFs is unavailable; current error propagation methods have simplifying assumptions that do not hold anymore with recent and upcoming telescopes so further development is required to define realistic requirements. The authors declare no conflict of interest and acknowledge funding from the TITAN ERA Chair project within the Horizon Europe Framework Program of the European Commission. They also list several open-source simulating and modelling software used in this review, including GALSIM, WEBBPSF, PHOSIM, WAVEDIFF, SHAPEPIPE, PIFF, MCCD, RCA, PSFEX TINY-TIM ,and PHOTUTILS .Overall ,this review provides a comprehensive overview of PSF modelling for astronomical telescopes with insights into current challenges ,future directions ,and potential solutions .