First Light Preparations of the 4m ILMT

Abstract

The 4[Formula: see text]m International Liquid Mirror Telescope (ILMT) is a zenith-pointing optical observing facility at ARIES Devasthal observatory (Uttarakhand, India). The first light preparatory activities of the ILMT were accomplished in April 2022 followed by on-sky tests that were carried out at the beginning of May 2022. This telescope will perform a multi-band optical (SDSS [Formula: see text], [Formula: see text] and [Formula: see text]) imaging of a narrow strip ([Formula: see text]) of sky utilizing the time-delayed integration technique. Single-scan ILMT images have an integration time of 102[Formula: see text]s and consecutive-night images can be co-added to further improve the signal-to-noise ratio. An image subtraction technique will also be applied to the nightly recorded observations in order to detect transients, objects exhibiting variations in flux or position. Presently, the facility is in the commissioning phase and regular operation will commence in March 2023. This paper presents a discussion of the main preparation activities before first light, along with preliminary results obtained.