Variabilidad intra-noche extrema en el blazar AO 0235+164

ROMERO, G. E.; CELLONE, S. A.; COMBI, J. A.

Tafí del Valle

Congreso; 44a. Reunión Anual AAA; 2000

AAA

We present results of two-colour photometry with high time resolution ofthe violently variable BL Lac object AO 0235+164. We have found extremeintranight variability with amplitudes of ~100 % over time scales of 24hours. Changes of 0.5 magnitudes in both R and V bands were measuredwithin a single night, and variations up to 1.2 magnitudes occurred fromnight to night. A complete outburst with an amplitude ~30 % was observedduring one of the nights, while the spectrum remained unchanged. Thisseems to support an origin based on a thin relativistic shockpropagating in such a way that it changes the viewing angle, as recentlysuggested by Kraus et al. (1999, A&A 344, 807) and Qian et al.(2000, A&A 357, 84).