J. Surdej is the Principal Investigator of the 4m International Liquid Mirror Telescope (ILMT) project which results from a collaboration between the Institute of Astrophysics and Geophysics (Liège University), the Canadian Astronomical Institutes from Vancouver (University of British Columbia), Québec (Laval University), Montréal (University of Montreal), Toronto (University of Toronto and York University) and Victoria (University of Victoria) and the Aryabhatta Research Institute of Observational Sciences (ARIES, India). Several colleagues from the Royal Observatory of Belgium, the Poznan Observatory (Poland), the Ulugh Beg Astronomical Institute of the Uzbek Academy of Sciences and National University of Uzbekistan have also joined the project.

The ILMT uses Liquid Mirror technology : the primary mirror of the telescope is a rotating container with highly-reflecting liquid in it (mercury). The surface of the spinning liquid takes the shape of a paraboloid.

The ILMT is a promising instrument which can be entirely dedicated to a specific scientific project. Indeed, its low cost makes it a unique survey instrument. As liquid mirror telescopes cannot be tilted, they cannot track like conventional telescopes do. The tracking is done artificially by using a technique called time delayed integration (TDI), which uses a CCD detector that tracks by electronically stepping its pixels. The ILMT will be equipped, at its prime focus, with a time-delay-integration (TDI) corrector capable of imaging a field of 30x30 arcminutes with a resolution better than one arcsecond. The ILMT will carry out direct imagery using a 4K x 4K thinned CCD as the detector working in the TDI mode.

It is installed at Devasthal (India) where it will monitor a strip of sky of 0.5 degree of declination down to a limiting magnitude of about 23 in the I band in a single integration. This survey will last for about five years. The information will be stored on disks so that the night observations can be coadded with a computer to lead to long equivalent integration times.

For more information see the link:

• http://www.ilmt.ulg.ac.be

• for the first ILMT light http://www.ilmt.ulg.ac.be/first-light-june-3rd-2022/