We have found a repeated, roughly 4-year cycle of radio variability of the -ray quasar 0202+149. We have found also that the start of the 3rd (and last) cycle examined by us coincides with the ejection of an apparent superluminally moving component. If other cycles are similarly related to component ejection, then we have established a regularity (although not a precise periodicity) in the time of ejection. The typical structure of the total flux density variability during the cycle, which was drawn on the basis of the observed cycles, can be explained by the variability of the VLBI core and features in the jet. The first flare of the cycle is caused mainly by an increase in the emission of the VLBI core connected with the ejection of a superluminal component, and the second flare of the cycle is probably caused by a change in the trajectory of the component. The similarity of the cycles of variability can be explained as the result of disturbances flowing down a jet containing a fixed underlying structure. The details of each cycle, such as the amplitude and spectrum, then depends on the strength of the disturbance, while the overall shape of the light curve is roughly the same from one cycle to the next.
If our picture corresponds to reality, then the next ejection of a superluminal component should be in 1998.5, which should result in an outburst at 37/43 GHz in 1999, and to an outburst at cm wavelengths about 0.7 year later.
© European Southern Observatory (ESO) 2000
Online publication: June 8, 2000