Intranight variability of 3C 454.3 during its 2010 November outburst
  Context. 3C 454.3 is a very active flat spectrum radio quasar (blazar) that has undergone a recent outburst in all observed bands, including the optical.   Aims. In this work we explore the short-term optical variability of 3C 454.3 during its outburst by searching for time delays between different optical bands. Finding one would be important for understanding the evolution of the spectrum of the relativistic electrons, which generate the synchrotron jet emission.   Methods. We performed photometric monitoring of the object by repeating exposures in different optical bands (BVRI). Occasionally, different telescopes were used to monitor the object in the same band to verify the reliability of the smallest variations we observed.   Results. Except on one occasion, where we found indications of a lag of the blue wavelengths behind the red ones, the results are inconclusive for most of the other cases. There were either no structures in the light curves to be able to search for patterns, or else different approaches led to different conclusions. 
R. Bachev, E. Semkov, A. Strigachev, B. Mihov, A. C. Gupta, S. Peneva,   E. Ovcharov, A. Valcheva, A. Lalova
astro-ph.HE astro-ph.CO