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Paper: Long-term Variation of AGNs
Volume: 159, BL Lac Phenomenon
Page: 99
Authors: Fan, J. H.; Xie, G. Z.; Adam, G.; Copin, Y.; Lin, R. G.; Bai, J. M.; Quin, Y. P.
Abstract: In this paper we will present the long-term variation in the optical and the infrared bands for some selected AGNs. 1. Some new optical data observed by us have been presented for BL Lacertae (1995-1996) and OJ 287 (1994-1995), and new infrared data are presented for OJ 287 (Nov=2E 1995), which corresponds to the second optical peak (Sillanpaa et al. 1996; Takalo et al. 1996) and during last outburst. 2. For objects with long term observations, the Jurkevich's method has been used to analyses the long-term variation period. It is interesting that the reported periods of AGNs are of the similar value of about 10 years: 3C 345 11.4 years (Webb et al. 1988), 3C 120 15 years (Belokon et al. 1987; Hagen-Thorn et al. 1997), ON 231 13.6 years (Liu et al. 1995), OJ 287 12 years (Sillanpaa et al. 1988; Kidger et al. 1992), PKS 0735+178 14 years (Fan et al. 1997), NGC 4151 15 years (Fan et al. 1998a), BL Lacertae 14.0 years (Fan et al. 1998b). Is the mechanism for the long-term variation the same for different AGNs? 3. The DCF method has been adopted to analysis the variation correlation in the optical and infrared bands for BL Lac object OJ 287, the results show that these two bands are strongly correlated, which suggest that the emission mechanism in the two bands is the same. 4. For the optical and infrared bands, the maximum variations are correlated.
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