Necessity of a TDI optical corrector for ILMT observations

The 4m International Liquid Mirror Telescope (ILMT) has recently achieved its first light at the ARIES Devasthal Observatory, Nainital, India. It is coupled with a 4k x 4k CCD camera and has a field of view of ~22 x 22 arc-min covering a total sky area of ~120 sq. degrees. ILMT will be unique as it will observe the same sky area towards the zenith direction every night and will perform a deep survey of that long and narrow strip by looking at all astronomical sources crossing its field of view. Since the science goals of any survey telescope rely heavily on the astrometry of the detected objects, we have developed a data reduction pipeline for the astrometric calibration of the data that will flow from the ILMT. Testing this pipeline on the data obtained from the ILMT in the commissioning phase, we have achieved a sub-arcsec accuracy in the astrometry of the detected objects, and the pipeline is ready to be implemented in real-time ILMT data. We will present the methodology involved in this data reduction pipeline and the first results on the astrometry based upon preliminary data obtained with the ILMT.