The infrared and optical variability of OJ 287

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
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: 19 March 1998
Accepted: 25 May 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 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: ; ; ; ; ; ; . 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.