Long-term, multi-frequency monitoring of the blazar S0528+134 (Nimfa)

Flux-density variations of the quasar S0528+134 (Nimfa) are analyzed based on long-term monitoring at five radio frequencies between 4.8 and 37 GHz, performed at the Crimean Astrophysical Observatory, the Metsähovi Radio Observatory of Aalto University, and the University of Michigan Radio Astronomy Observatory. The dynamics of a powerful flare in 1996 are analyzed using gamma-ray (0.1–300 GeV), X-ray (2–10 keV, 15–50 keV), and radio observations. The delays of the flare between different spectral ranges and between different radio wavelengths have been measured. The dependence for the delays at different radio wavelengths relative to the X-ray and optical flares is established based on long-term observations in the X-ray, optical, and radio obtained from 2004 to 2013. Multi-frequency monitoring in the radio is used to estimate the orbital and precession periods in the binary supermassive black hole system S0528+134 and the physical characteristics of this system.