Multi-wavelength activity of blazar 3C 454.3

Astronomer's Telegram #5423 V. M. Larionov, D. A. Morozova, N. V. Efimova (St. Petersburg Univ. and Pulkovo Observatory, Russia), D. A. Blinov (Univ. of Crete, Greece; St. Petersburg Univ., Russia), A. Di Paola (INAF - Osservatorio Astronomico di Roma, Monte Porzio, Italy)

on 26 Sep 2013; 18:53 UT

In addition to ATel#5411 and in reference to ATel#5412 and ATel#5418 we report that recently announced flare of the blazar 3C 454.3 seems to have culminated at 2013 September 25. Our optical (AZT-8, Crimea) and NIR (AZT-24, Campo Imperatore, Italy) photometric measurements taken this night yield, correspondingly, R=13.427 at JD2456561.336 and J=11.67 at JD2456561.259. Afterwards we see a clear decline (0.1 mag) in all bands. This outburst is accompanied by very high level of optical polarization: 33% during the nights of September 24 and 25. We notice that the positional angle of polarization is approximately perpendicular to the direction of the VLBA jet. The maximum level of Fermi gamma-ray flux is rather modest, 5.0E-6 ph cm^-2 s^-1. Figure shows the evolution of optical flux and polarization parameters, and also gamma-ray behaviour, during last month. It may be noted that previous outbursts of this blazar had multiple structure (Jorstad et al, 2013, ApJ, 773, 147), and a renewed activity may be expected within 2-3 weeks . We got also NIR spectrum of 3C454.3 during the night of September 25 and found that the flux in H_alpha is now (2.8+/-03)E-16 W m-2, that is markedly more than during moderately faint state of 2007, when it was in the range of [2.0-2.5] E-16 W m-2 (Raiteri et al, 2008, A&A, 491, 755) It may reflect a higher level of current BLR activity than that seen in 2007.