• JEAN SURDEJ

      Articles written in Journal of Astrophysics and Astronomy

    • Quasar catalogue for the astrometric calibration of the forthcoming ILMT survey

      AMIT KUMAR MANDAL BIKRAM PRADHAN JEAN SURDEJ C. S. STALIN RAM SAGAR BLESSON MATHEW

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      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.

    • Upcoming 4m ILMT facility and data reduction pipeline testing

      BRAJESH KUMAR VIBHORE NEGI BHAVYA AILAWADHI SAPNA MISHRA BIKRAM PRADHAN KUNTAL MISRA PAUL HICKSON JEAN SURDEJ

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      The 4m international liquid mirror telescope (ILMT) installation activities have recently been completed at the Devasthal observatory (Uttarakhand, India). The ILMT will perform continuous observation of a narrow strip of the sky ($\sim$27$'$) passing over the zenith in the SDSS $g'$, $r'$ and $i'$ bands. Incombination with a highly efficient 4k$\times$4k CCD camera and an optical corrector, the images will be secured at the prime focus of the telescope using the time delayed integration technique. The ILMT will reach $\sim$22.5mag ($g'$-band) in a single scan and this limiting magnitude can be further improved by co-adding the nightly images. The uniqueness of the one-day cadence and deeper imaging with the ILMT will make it possible to discover and study various galactic and extra-galactic sources, specially variable ones. Here, we present the latest updates of the ILMT facility and discuss the preparation for the first light, which is expected during early 2022. We also briefly explain different steps involved in the ILMT data reduction pipeline.

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    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

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      Posted on July 25, 2019

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