Frequency-dependent time delays for strong outbursts in four blazars from the Metsahovi and UMRAO monitoring databases

The combined data of the University of Michigan Radio Astronomy Observatory and Metsähovi Radio Observatory provide us with radio light curves for active galactic nuclei monitored by both observatories from 4.8 to 37 GHz covering time-intervals up to ∼25 yr. We consider here such composite light curves for four gamma-ray blazars that have been nearly continuously monitored at both observatories: 0...