Carnerero Martin, Maria Isabel

Optical-gamma correlation in BL Lacertae

 Author list: C. M. Raiteri, M. Villata and M. I. Carnerero for the GASP-WEBT collaboration

The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT; http://www.oato.inaf.it/blazars/webt/) collaboration was started in 2007. The aim was to perform continuous monitoring of selected blazars at low frequencies to compare with the high-energy observations of the gamma-ray satellites. BL Lacertae is one of the sources followed by the GASP and Fermi has provided a continuous gamma-ray light curve since 2008. Here we present an analysis of the optical and gamma-ray flux behaviour of BL Lacertae from 2008 to 2012, including the 2011-2012 outburst. A general correlation is found between the fluxes at the two frequencies. However, the details of the emission behaviour require a more complex explanation than simple co-spatiality of the production sites.