Multi-CCD modelling of the point spread function

Context. Galaxy imaging surveys observe a vast number of objects, which are ultimately affected by the instrument’s point spread function (PSF). It is weak lensing missions in particular that aimed at measuring shape galaxies and PSF effects represent an significant source systematic errors must be handled appropriately. This requires high level accuracy modelling stage as well estimation galaxy positions. Aims. The goal this work to estimate positions, also referred non-parametric starts from set noisy star image observations distributed over focal plane. To accomplish this, we need our model precisely capture field variations view then recover chosen Methods. In paper, propose new method, coined Multi-CCD (MCCD) modelling, simultaneously creates entirety allows us global local features through use two complementary models enforce different spatial constraints. Most existing build one per charge-coupled device, can lead difficulties capturing ellipticity patterns. Results. We first tested method on realistic simulated dataset, comparing it with state-of-the-art methods (PSFEx RCA) finding outperforms both them. Then contrasted approach PSFEx based real data Canada-France Imaging Survey, uses Canada-France-Hawaii Telescope. show less achieves ∼22% gain pixel’s root mean square error respect . Conclusions. present share code for algorithm all plane mature enough handle data.