2013A&A...555A.138F

We have reanalyzed the giant outburst of the blazar PKS 1510-089 (z=0.36) that occurred on 2011 October-November. The γ-ray flux in the 0.1-100GeV energy range exceeded the value of 10^–5ph/cm2/s for several days. The peak flux was reached on 2011 October 19, with a value of ∼4.4x10^–5ph/cm2/s, which in turn corresponds to a luminosity of ∼ 2x10⁴⁹erg/s. A very short timescale variability was measured. Particularly on 2011 October 18, the flux-doubling time was as short as ∼20 min. This is the shortest variability ever detected in the MeV-GeV energy band. We compared our analysis with two other outbursts observed in 2009 March and 2012 February-March, when the blazar was also detected by H.E.S.S. and MAGIC to infer information about the emission at hundreds of GeV.