SIMBAD references

We have analyzed the radio light curves of PKS 1510-089 at 37 and 22 GHz from 1990 to 2005 taken from the database of the Metsähovi Radio Observatory, and find evidence of quasi-periodic outbursts. The light curves show great activity with very complicated non-sinusoidal variations. Using Jurkervich's method, the power spectrum method, and the discrete autocorrelation function to analyze these data, we have found two periods of p₁= 0.92±0.04 yr and p₂= 1.82±0.12 yr for the outbursts in PKS 1510-089. It is interesting to note that the results for two frequencies and three methods are almost the same and p₂~ 2p₁. In addition, these results are in good agreement with the periodic deep flux minima of 1.84±0.1 yr (half period ∼ 0.92±0.03 yr) observed by us and other authors in the optical band in 2002, 2004, and 2005.