An Analysis of the Periods of the Radio Light Curves of the Blazar 3C 446

We compiled all published observational data of the Blazar 3C 446 at 8GHz, 4.8GHz, 14GHz, and 22GHz from 1977 to 2006, and derived light curves at the four frequencies. The light curves show violent activities of 3C 446. Using the PERIOD04 analysis software, we have found that there is a period of 7.2 years in the light curves, which is consistent with the results found by us using the wavelet analysis method. The PERIOD04 can be used to extract periods of discrete data. It is a mature software of relatively simple steps which provides convenience in calculating periods of data. It has been successfully used in solar physics, but not in any previous research of Active Galactic Nuclei (AGN). We have tested the applicability of the PERIOD04 for AGN light curves by using it on simulated AGN data. The tests show the validity of the software for analyzing AGN light curves. We also discuss the effects of signal-to-noise ratios on the results. From the result of the period, we estimate the radius of the instability region of 3C 446 to be r=123.83r_g.