The infrared and optical variability of OJ 287

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.(m)72; Delta B = 5.(m)93; Delta V = 5.(m)18; Delta R = 4.(m)45; Delta I = 4.(m)07; Delta J = 3.(m)87; Delta H = 3.(m)78; Delta K = 3.(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.