Optical monitoring of 3C 390.3 from 1995 to 2004 and possible periodicities in the historical light curve

摘要

We report V, R, and I band CCD photometry of the radio galaxy 3C 390.3 obtained with the 1.56 m telescope of the Shanghai Astronomical Observatory from 1995 March to 2004 August. Combining these data with data from the literature, we have constructed a historical light curve from 1894 to 2004 and searched for periodicities using the CLEANest program. We find possible periods of 8.30 +/- 1.17, 5.37 +/- 0.49, 3.51 +/- 0.21, and 2.13 +/- 0.08 yr.