H-alpha monitoring of OJ 287 in 2005-08^*

¹ Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland e-mail: kani@utu.fi
² Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland

Received: 4 February 2010
Accepted: 9 April 2010

Abstract

We present the results of Hα monitoring of the BL Lac object OJ 287 with the VLT during seven epochs in 2005-08. We were able to detect five previously undetected narrow emission lines, λλ6548, 6583[NII], λ6563Hα and λλ6716, 6731 [SII] during at least one of the epochs and a broad Hα feature during two epochs. The broad Hα luminosity was a factor ~10 lower in 2005-08 than in 1984 when the line was previously detected and a factor ~10 lower than what is observed in quasars and Seyfert galaxies at the same redshift. The data are consistent with no change in the position or luminostity of the Hα line in 2005-08. The width of the Hα line was 4200 ± 500 km s^-1, consistent with the width in 1984.