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Optical brightening of blazar S4 0954+658

ATel #3220; V. M.Larionov, D. A.Morozova, I. S.Troitsky, D. A.Blinov, E. N.Kopatskaya, E. G.Larionova (Astron. Inst. of St. Petersburg University, Russia)
on 14 Mar 2011; 22:44 UT
Credential Certification: V. Larionov (vlar@astro.spbu.ru)

Subjects: Optical, Gamma Ray, Request for Observations, AGN, Blazar, Quasar

Referred to by ATel #: 6996, 7046, 7055, 7750, 8445, 10327, 16010

We perform optical photopolarimetric observations of blazar S4 0954+658 with 70-cm telescope in Crimea and 40-cm telescope in St.Petersburg. We report that after a faint state with the level around R ~ 17.6 registered in the first half of January, the optical brightness of the source started to increase in the end of 2011 January, reaching ~15.7 during last two weeks (2011 March 1-14) and showing flare-like behaviour. The most spectacular case of intranight variability was demonstrated during the night of 2011 March 9 UT, when we observed brightening by ~ 0.7 mag within ~ 7 hours. This is also worth to notice that the position angle of optical polarization of S4 0954+658 was a subject of smooth rotation by about 200 degrees during the last month. Our preliminary light curve can be found at a link below. We analysed open-access Fermi-LAT data and did not see any sign of increased gamma-ray activity above detection threshold but for the date of 2011 March 5 UT, JD2455626, remarkably coincident with the local optical maximum. Multiwavelength observations of the source are strongly encouraged.

S4 0954+658 light curve