Astrometric and Photometric Standard Candidates for the Upcoming 4-m International Liquid Mirror Telescope Survey

Abstract

The International Liquid Mirror Telescope (ILMT) is a 4-m class survey telescope that has recently achieved first light and is expected to swing into full operations by January 1, 2023. It scans the sky in a fixed [Formula: see text] wide strip centered at the declination of [Formula: see text] and works in Time Delay Integration (TDI) mode. We present a full catalog of sources in the ILMT strip that can serve as astrometric calibrators. The characteristics of the sources for astrometric calibration are extracted from Gaia EDR3 as it provides a very precise measurement of astrometric properties such as RA ([Formula: see text]), Dec ([Formula: see text]), parallax ([Formula: see text]), and proper motions ([Formula: see text] & [Formula: see text]). We have crossmatched the Gaia EDR3 with SDSS DR17 and PanSTARRS-1 (PS1) and supplemented the catalog with apparent magnitudes of these sources in [Formula: see text], and i filters. We also present a catalog of spectroscopically confirmed white dwarfs with Sloan Digital Sky Survey (SDSS) magnitudes that may serve as photometric calibrators. The catalogs generated are stored in an SQLite database for query-based access. We also report the offsets in equatorial positions compared to Gaia for an astrometrically calibrated TDI frame observed with the ILMT.