Year: 2026
Type: preprint
Abstract: We have devised an approach to model the empirical Point Spread Function (PSF) of the images taken with the 4-meter International Liquid Mirror Telescope (ILMT). The characteristics of the ILMT PSF are influenced by the nature of the Liquid Mirror, as well as by instrument specific and atmospheric factors. As the telescope uses Time Delay Integration (TDI) mode for tracking the passing objects, the PSF varies along the declination axis due to differential motion and star-trail curvature. The 5-element optical corrector homogenizes the PSF to some degree, but does not completely eliminate the disturbing effects mentioned above. The PSF in the RA direction is changing due to the sky conditions. We show that we can successfully model the PSF of 4k$\times$4k chunks using PSFEx, accounting for second-order X-Y variability. Our software robustly reproduces the PSF and its variation across the field.
Source: arXiv (Cornell University)
Language: English
Subfield: Instrumentation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: Arthritis National Research Foundation, York University, European Commission, Department of Science and Technology, Ministry of Science and Technology, India, Fonds De La Recherche Scientifique - FNRS, Belgian Federal Science Policy Office, Université de Liège, Natural Sciences and Engineering Research Council of Canada, Science and Engineering Research Board
Awards: G595755496, G832689143
OpenAlex ID: W7221816770