2000/07/26 by G. E. Romero, Gustavo E. Romero, Romero, G. E. +4
Engineering · Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #Particle Accelerators and Free-Electron Lasers #Particle physics theoretical and experimental studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0007407
4 pages, 3 figures, to appear in Astronomy & Astrophysics (Letters)
arxiv created 2000/07/26 · openalex publication_date 2000/07/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present results of two-colour photometry with high time resolution of the violently variable BL Lac object AO 0235+164. We have found extreme intranight variability with amplitudes of ~ 100 % over time scales of 24 hours. Changes of 0.5 magnitudes in both R and V bands were measured within a single night, and variations up to 1.2 magnitudes occurred from night to night. A complete outburst with an amplitude ~ 30 % was observed during one of the nights, while the spectrum remained unchanged. This seems to support an origin based on a thin relativistic shock propagating in such a way that it changes the viewing angle, as recently suggested by Kraus et al. (1999) and Qian et al. (2000).