Continuum reverberation mapping in a z = 1.41 radio-loud quasar
  Q0957+561 was the first discovered gravitationally lensed quasar. The mirage
shows two images of a radio-loud quasar at redshift z = 1.41. The time lag
between these two images is well established around one year. We detected a
very prominent variation in the optical brightness of Q0957+561A at the
beginning of 2009, which allowed us to predict the presence of significant
intrinsic variations in multi-wavelength light curves of Q0957+561B over the
first semester of 2010. To study the predicted brightness fluctuations of
Q0957+561B, we conducted an X-ray, NUV, optical and NIR monitoring campaign
using both ground-based and space-based facilities. The continuum NUV-optical
light curves revealed evidence of a centrally irradiated, standard accretion
disk. In this paper, we focus on the radial structure of the standard accretion
disk and the nature of the central irradiating source in the distant radio-loud
active galactic nucleus (AGN).
