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Theme: Other creative topics in astronomical software
Nowadays, astronomers perform point spread function (PSF) fitting for most types of observational data. Interpolation of the PSF is often an intermediate step in such algorithms. The scope of the PSF interpolation challenge is illustrated by fundamental astrophysical tasks. HST WFC3 PSF interpolation (including interpolation over the focal plane) has implications for cosmological constants measurements. In the case of the Multi-AO Imaging Camera for Deep Observations (MICADO) at the Extremely Large Telescope (ELT), PSF interpolation will play a crucial role in high-precision astrometry of globular clusters and confirmation of the presence of intermediate-mass black holes. The Enhanced Resolution Imager and Spectrograph (ERIS) on the Very Large Telescope (VLT) is a recently commissioned analogue of the upcoming MICADO@ELT. Significant PSF variations across the field of view invalidate the approach of deconvolving with the mean PSF or on-axis PSF. This can be unsatisfactory when performing Single Conjugate Adaptive Optics (SCAO) observations, as these sophisticated and expensive systems are designed to achieve high resolution with ground-based telescopes by correcting for atmospheric turbulence in the direction of one reference star.
Our study aims to demonstrate how interpolation techniques affect scientific outcomes. To test it, we applied interpolation algorithms to the simulated SCAO-assisted MICADO@ELT, ERIS@VLT, and empirical HST WFC3 PSF grids. We use cross-validation and calculate physical-motivated metrics as well as probabilistic metrics. Through our investigation, we shed light on the nuanced challenges posed by PSF interpolation and emphasize its critical implications for advancing our understanding of the Universe.