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      https://www.ias.ac.in/article/fulltext/joaa/041/0022

    • Keywords

       

      Quasars; parallaxes; proper motions; ILMT; astrometry.

    • Abstract

       

      Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax. The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will survey the sky that covers a width of about 27$'$. To carry out astrometric calibration of theILMT observations, we aimed to compile a list of quasars with accurate equatorial coordinates and falling in the ILMT stripe. Towards this, we cross-correlated all the quasars that are known till the present date with the sources in the Gaia-DR2 catalogue, as the Gaia-DR2 sources have position uncertainties as small as a few milli arcsec (mas). We present here the results of this cross-correlation which is a catalogue of 6738 quasars that is suitable for astrometric calibration of the ILMT fields. In this work, we present this quasar catalogue. This catalogue of quasars can also be used to study quasar variability over diverse time scales when the ILMT starts its observations. While preparing this catalogue, we also confirmed that quasars in the ILMT stripe have proper motion and parallax lesser than 20 mas yr$^{-1}$ and 10 mas, respectively.

    • Author Affiliations

       

      AMIT KUMAR MANDAL1 2 BIKRAM PRADHAN3 JEAN SURDEJ4 C. S. STALIN2 RAM SAGAR2 BLESSON MATHEW1

      1. Department of Physics, CHRIST (Deemed to be University), Hosur Road, Bangalore 560 029, India.
      2. Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India.
      3. Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 001, India.
      4. Space Science, Technologies and Astrophysics Research (STAR) Institute, Universite´ de Lie`ge, Alle´e du 6 Aouˆ t 19c, 4000 Lie`ge, Belgium.
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