Odessa Astronomical Publications (Nov 2012)

TIME DELAY BETWEEN IMAGES OF THE LENSED QUASAR UM673

  • E. Koptelova,
  • W. P. Chen,
  • T. Chiueh,
  • B. P. Artamonov,
  • V. L. Oknyanskij,
  • S. N. Nuritdinov,
  • O. Burkhonov,
  • T. Akhunov,
  • V. V. Bruevich,
  • O. V. Ezhkova,
  • A. S. Gusev,
  • A. V. Sergeyev,
  • Sh. A. Ehgamberdiev,
  • M. A. Ibragimov

DOI
https://doi.org/10.18524/1810-4215.2012.25.83310
Journal volume & issue
Vol. 25, no. 2
pp. 169 – 171

Abstract

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We study brightness variations in the double lensed quasar UM673 (Q0142-100) with the aim of measuring the time delay between its two images. Methods.. We analyzed the V, R and I-band light curves of the A and B images of UM673, which cover ten observational seasons from August 2001 to November 2010. We also analyzed the time evolution of the difference in magnitudes (flux ratio) between images A and B of UM673 over more than ten years. We find that the quasar exhibits both short-term (with an amplitude of ~ 0.1 mag in the R band) and long-term (with an amplitude of ~ 0.3 mag) variability on timescales of about several months and several years, respectively. These brightness variations are used to constrain the time delay between the images of UM673. From a cross-correlation analysis of the A and B quasar light curves and an error analysis we measure a mean time delay of 89 days with an rms error of 11 days.