Multi-Wavelength Analysis of the Quasar CTA102 during a Dramatic Outburst in 2016 December

Abstract: The quasar CTA102 underwent a dramatic outburst from gamma-ray toradio wavelengths in late 2016. The gamma-ray emission at 0.1-200 GeV roseup to (12.1+-0.7)x10^{-6} phot/s/cm^2, with a significant flattening of the spectral index. The blazar reached an optical brightness level never observed previously, <11 mag in R band, and an increase of the radio flux density at millimeter wavelengths with flattening of the radio spectrum was observed as well.We present analysis of multi-wavelength data during the event obtained at gamma-rays with the Fermi Large Area telescope, at X-rays provided by the NuStar X-ray telescope and Swift XRT and UVOT, in optical bands measured at different telescopes around the world along with polarimetric observations, and at mm-waves obtained at Metsahovi Radio Observatory and SubMillimeter Array, along with imaging of theparsec-scale jet of the quasar with the VLBA at 43 GHz. This research is funded in part by NASA through Fermi Guest Investigator grant NNX14AQ58G and by the National Science Foundation through grant AST-1615796.