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Optical and radio brightening of BL Lacertae

ATel #4271; Sh. A. Ehgamberdiev and D. O. Mirzaqulov (Ulugh Beg Astronomical Institute, Maidanak Observatory, Uzbekistan), C. S. Buemi, P. Leto, C. Trigilio and G. Umana (INAF, Osservatorio Astrofisico di Catania, Italy), C. M. Raiteri and M. Villata (INAF, Osservatorio Astrofisico di Torino, Italy), U. Bach (Max-Planck-Institut fuer Radioastronomie, Bonn, Germany) for the GASP Collaboration
on 23 Jul 2012; 10:57 UT
Credential Certification: Claudia M. Raiteri (raiteri@oato.inaf.it)

Subjects: Radio, Optical, Blazar

Referred to by ATel #: 4277, 4557, 4565, 4973

Optical observations at the Mount Maidanak Observatory in the framework of the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) reveal a rapid optical brightening of BL Lacertae. This is one of the 28 blazars for which the GASP performs a long-term, multiwavelength monitoring. The source brightness has recently increased from R = 13.66 +/- 0.01 on July 19.82 to R = 12.60 +/- 0.01 on July 22.97. This episode is similar to those occurred in June 2012 (Atel #4155) and May 2011 (ATel #3371), which led the source to brightness levels comparable to those reached during the historical outbursts of 1997-2004.
A bright state has also been observed at 43 GHz with the Noto radio telescope, with an average flux density of 8.3 +/- 0.7 Jy on July 21-22.