ON the Character of Optical Variability of the Quasar 3c 273

Optical monitoring of BL Lac object S5 0716+714 and FSRQ 3C 273 from 2000 to 2014

“…There are many sources showing quasi-periods, such as 3C 273, 3C 279, 3C 454.3, Mrk335, Mrk 421, Mrk 501, OJ287, 0109+224, 0735+178, 2200+420, and so on (Kunkel 1967;Sillanpaa et al 1988;Chertoprud et al 1973;Stickel et al 1993;Fan et al 1998Fan et al , 2007Fan et al , 2014Fan & Lin 2000;Xie et al 2002;Raiteri et al 2001;Ciprini et al 2003). Explanation of the long-term variations could be based on the binary black-hole model, the thermal instability model or the perturbation model, and so on (Fan et al 2007).…”

The 11 Year Period in OJ 287 Revisited: Is It a True Long-Enduring Period?

“…(Sillanpa a 2.1. Data Sampling and Its Impact on Period Searches Although considerable advances have been made in data analysis since the earliest work on quasar light curves and techniques such as Deeming (1975) analysis, the CLEAN algorithm, and the Jurkevich (1971) method of periodogram analysis are capable of analysis of unevenly sampled data, a light curve such as that of OJ 287 still presents a considerable challenge. Chaos analysis of the OJ 287 historical light curve has been unsuccessful (Sadun 1995) because it requires the data sampling to be even, and in the process of obtaining evenly sampled data, vital information is lost.…”

“…Chaos analysis of the OJ 287 historical light curve has been unsuccessful (Sadun 1995) because it requires the data sampling to be even, and in the process of obtaining evenly sampled data, vital information is lost. Although Deeming (1975) analysis, the best known form of Fourier transform analysis of light curves, gives reliable results for unevenly sampled data, the method fails in certain circumstances, particularly when data sampling is especially heavily weighted to certain epochs.…”

“…Given that the outbursts do not comply with this condition, standard analyses such as Deeming (1975) analysis, Jurkevich (1971 analysis, or chaos analysis cannot give a reliable period for the light curve. Similarly, they are unable even to deÐne whether or not such a period even exists in the full lightcurve record.…”

“…Two objects in particular were the focus of attention. Various studies (e.g., Kunkel 1967 ;Chertoprud, Gudzenko, & Ozernoy 1973) suggested that 3C 273 presents a period of 13 yr in its historical light curve from 1887 to the epoch of its discovery. This, however, depends largely on a single well-observed cycle of the suggested period around the 1930s.…”