即将进行的ILMT巡天天体测量校准用类星体目录
Quasar catalogue for the astrometric calibration of the forthcoming ILMT survey
摘要：
类星体的自行和视差可以忽略不计，是大规模天文测量中进行天体测量校准的理想目标。即将到来的4米国际液体镜望远镜（ILMT）将测量覆盖约27弧分宽度的天空。为了对ILMT观测进行天体测量校准，我们的目标是编制一份具有精确赤道坐标并落入ILMT条纹的类星体列表。为此，我们将迄今为止已知的所有类星体与Gaia-DR 2目录中的源进行了交叉相关，因为Gaia-DR 2源的位置不确定性小至几毫角秒（mas）。我们在这里提出的结果，这种互相关是一个目录的6738类星体，适合于天体测量校准的ILMT领域。在这项工作中，我们提出了这个类星体目录。当ILMT开始观测时，这个类星体目录也可以用来研究类星体在不同时间尺度上的变化。在编制这份星表的同时，我们还证实了ILMT条纹中的类星体的自行和视差分别小于20 mas/yr和10 mas。
英文摘要：
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.
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