Astron. Astrophys. Suppl. Ser. 133, 163-169

The infrared and optical variability of OJ 287

J.H. Fan^1,2,3 - G. Adam¹ - G.Z. Xie⁴ - S.L. Cao⁵ - R.G. Lin² - Y.P. Qin⁴ - Y. Copin ¹ - J.M. Bai⁴ - X. Zhang⁴ - K.H. Li⁴

1 - CRAL Observatoire de Lyon, 9 avenue Charles André, 69563 Saint-Genis-Laval Cedex, France
2 - Center for Astrophysics, Guangzhou Normal University, Guangzhou 510400, China
e-mail: jhfan@guangztc.edu.cn
3 - Joint Laboratory for Optical Astronomy, Chinese Academy of Sciences, China
4 - Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011, China
5 - Department of Astronomy, Beijing Normal University, Beijing, China

Received March 19; accepted May 25, 1998

Abstract:

In this paper, the long-term historical optical (UBVRI) and near-infrared (JHK) data are presented with some new observations in the optical (February 1994-January 1995) and near-infrared (November 1995) bands included for BL Lac object OJ 287. The new optical data in V-band are in agreement with the results reported by other authors (Sillanpaa et al. 1996a; Arimoto et al. 1997), a close correlation between the color index of B-V and the magnitude V has been obtained from our new observations. The new infrared observations presented here indicate that the source was at a high level in the infrared band during the observation period. From the available literature, we have got that the largest variations for UBVRIJHK bands are respectively: $\Delta U = 4\hbox{$.\!\!^{\rm m}$}72$; $\Delta B = 5\hbox{$.\!\!^{\rm m}$}93$; $\Delta V = 5\hbox{$.\!\!^{\rm m}$}18;$ $\Delta R = 4\hbox{$.\!\!^{\rm m}$}45$; $\Delta I = 4\hbox{$.\!\!^{\rm m}$}07$; $\Delta J = 3\hbox{$.\!\!^{\rm m}$}87$; $\Delta H = 3\hbox{$.\!\!^{\rm m}$}78$; $\Delta K = 3\hbox{$.\!\!^{\rm m}$}54$. A strong correlation is found between the optical and near-infrared bands when the DCF method is used, which suggests that these two bands have the same emission mechanism.

Key words: BL Lacertae objects: individual: OJ 287; general -- infrared: galaxies