EDP Sciences
Free access
Volume 440, Number 1, September II 2005
Page(s) 53 - 58
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20052852

A&A 440, 53-58 (2005)
DOI: 10.1051/0004-6361:20052852

Microlensing in the double quasar SBS 1520+530

E. R. Gaynullina1, R. W. Schmidt2, T. Akhunov1, 3, O. Burkhonov3, S. Gottlöber4, K. Mirtadjieva1, 3, S. N. Nuritdinov1, 3, I. Tadjibaev1, 3, J. Wambsganss2 and L. Wisotzki4

1  National University of Uzbekistan, Physics Faculty, Tashkent 700174, Uzbekistan
2  Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, 69120 Heidelberg, Germany
    e-mail: rschmidt@ari.uni-heidelberg.de
3  Ulugh Beg Astronomical Institute of the Uzbek Academy of Sciences and Isaac Newton Institute of Chile, Uzbek Branch, Astronomicheskaya 33, Tashkent 700052, Uzbekistan
4  Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany

(Received 9 February 2005 / Accepted 13 May 2005)

We present the results of a monitoring campaign of the double quasar SBS 1520+530 at Maidanak observatory from April 2003 to August 2004. We obtained light curves in V and R filters that show small-amplitude $\Delta m\approx 0.1$ mag intrinsic variations of the quasar on time scales of about 100 days. The data set is consistent with the previously determined time delay of $\Delta t=(130\pm3)$ days by Burud et al. (2002, A&A, 391, 481). We find that the time delay corrected magnitude difference between the quasar images is now larger by $(0.14\pm0.03)$ mag than during the observations by Burud et al. (2002). This confirms the presence of gravitational microlensing variations in this system.

Key words: gravitational lensing -- dark matter -- quasars: individual: SBS 1520+530 -- cosmology: observations

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