• An alternative scheme to estimate AstroSat/LAXPC background for faint sources

    • Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/042/0055

    • Keywords

       

      AstroSat/LAXPC; instrument background; calibration.

    • Abstract

       

      An alternative scheme is described to estimate the layer 1 LAXPC 20 background for faint sources where the source contribution to the 50–80 keV count rate is less than 0.25 counts/s (15 milli-crabs or $6\times 10^{-11}$ ergs/s/cm$^2$). We consider 12 blank sky observations and based on their 50–80 keV count rate in 100 second time-bins, generate four template spectra which are then used to estimate the background spectrum and lightcurve for a given faint source observation. The variance of the estimated background subtracted spectra for the 12 blank sky observations is taken as the energy dependent systematic uncertainty which will dominate over the statistical one for exposures longer than 5 ks. The estimated 100 second time bin background lightcurve in the 4–20 keV band with a 3% systematic error matches with the blank sky ones.The 4–20 keV spectrum can be constrained for a source with flux $\gtrapprox$1 milli-crab. Fractional rms variability of 10% can be determined for a $\sim$5 milli-crab source lightcurve binned at 100 seconds. To illustrate the scheme, the lightcurves and spectra of three different blank sky observations, three AGN sources (Mrk 0926, Mrk 110, NGC 4593) and LMC X-1 are shown.

    • Author Affiliations

       

      RANJEEV MISRA1 JAYASHREE ROY1 J. S. YADAV2

      1. Inter-University Centre for Astronomy and Astrophysics, Pune 411 007, India.
      2. Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016, India.
    • Dates

       
  • Journal of Astrophysics and Astronomy | News

    • 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.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.