Optical polarimetric and multiwavelength flaring activity of blazar 3C279

An exhaustive analysis of 9-year optical R-band photopolarimetric data of the flat-spectrum radio quasar 3C279 from 2008 February 27 to 2017 May 25 is presented, alongside with multiwavelength observing campaigns performed during the flaring activity exhibited in 2009 February/March, 2011 June, 2014 March/April, 2015 June and 2017 February. In the R-band, this source showed the maximum brightness state of $13.68\pm 0.11$ mag ($1.36\pm0.20$ mJy) on 2017 March 02, and the lowest brightness state ever recorded of $18.20\pm 0.87$ mag ($0.16\pm0.03$ mJy) on 2010 June 17. During the entire period of observations, the polarization degree varied between $0.48\pm0.17$% and $31.65\pm0.77$% and the electric vector position angle exhibited large rotations between $82.98^\circ \pm0.92$ and $446.32^\circ \pm1.95$. Optical polarization data show that this source has a stable polarized component that varied from $\sim$6% (before the 2009 flare) to $\sim$13% after the flare. The overall behavior of our polarized variability data supports the scenario of jet precessions as responsible of the observed large rotations of the electric vector position angle. Discrete correlation function analysis show that the lags between gamma-rays and X-rays compared to the optical R-band fluxes are $\Delta t \sim$ 31 d and $1$ d in 2009. Lags were also found among gamma-rays compared with X-rays and radio of $\Delta t \sim$ 30 d and $43$ d in 2011, and among radio and optical-R band of $\Delta t \sim$ 10 d in 2014. A very intense flare in 2017 was observed in optical bands with a dramatic variation in the polarization degree (from $\sim$ 6% to 20%) in 90 days without exhibiting flaring activity in other wavelengths.