Quasar catalogue for the astrometric calibration of the forthcoming ILMT
  survey
  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 arcminute. To carry out astrometric
calibration of the ILMT 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 and 10
mas, respectively.
