First light preparations of the 4m ILMT

TL;DR

The paper discusses the preparation, initial testing, and early results of the 4m ILMT, a new optical telescope in India designed for wide-field sky surveys and transient detection, set to begin regular operations in October 2022.

Contribution

It details the first light preparations and early on-sky tests of the ILMT, highlighting its unique multi-band imaging and transient detection capabilities.

Findings

Successful completion of first light preparations in April 2022

Preliminary on-sky test results demonstrating system functionality

Readiness for regular operations starting October 2022

Abstract

The 4m 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 $g'$, $r'$ and $i'$) imaging of a narrow strip (~$22'$) of sky utilizing the time-delayed integration technique. Single-scan ILMT images have an integration time of 102 sec 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 October 2022, after the monsoon. This paper presents a discussion of the main preparation activities before first light, along with preliminary results obtained.