Historical optical maximum of BL Lacertae

Astronomer's Telegram #5597 V. M. Larionov and T. S. Konstantinova (Astron. Inst., St.-Petersburg State Univ., Russia), C. M. Raiteri and M. Villata (INAF, Osservatorio Astrofisico di Torino, Italy)

on 25 Nov 2013; 08:55 UT

We report on optical observations of BL Lacertae carried out at the Crimean and St.-Petersburg observatories in the framework of the GASP-WEBT collaboration.

Starting from early 2013, when the source was observed at its historical minimum levels (R about 15.2), BL Lacertae has shown an almost continuous brightening until November 23.9, when it reached R = 12.34. This is the maximum optical brightness level ever detected, a bit higher than that observed during the 1997 outburst (see e.g. Villata et al. 2004, A&A, 421, 103).