Bibcode
Pursimo, T.; Takalo, L. O.; Sillanpää, A.; Kidger, M.; Lehto, H. J.; Heidt, J.; Charles, P. A.; Aller, H.; Aller, M.; Beckmann, V.; Benítez, E.; Bock, H.; Boltwood, P.; Borgeest, U.; de Diego, J. A.; De Francesco, G.; Dietrich, M.; Dultzin-Hacyan, D.; Efimov, Y.; Fiorucci, M.; Ghisellini, G.; González-Pérez, N.; Hanski, M.; Heinämäki, P.; Honeycutt, R. K.; Hughes, P.; Karlamaa, K.; Katajainen, S.; Knee, L. B. G.; Kurtanidze, O. M.; Kümmel, M.; Kühl, D.; Lainela, M.; Lanteri, L.; Linde, J. V.; Lähteenmäki, A.; Maesano, M.; Mahoney, T.; Marchenko, S.; Marscher, A.; Massaro, E.; Montagni, F.; Nesci, R.; Nikolashvili, M.; Nilsson, K.; Nurmi, P.; Pietilä, H.; Poyner, G.; Raiteri, C. M.; Rekola, R.; Richter, G. M.; Riehokainen, A.; Robertson, J. W.; Rodríguez-Espinoza, J.-M.; Sadun, A.; Shakhovskoy, N.; Schramm, K. J.; Schramm, T.; Sobrito, G.; Teerikorpi, P.; Teräsranta, H.; Tornikoski, M.; Tosti, G.; Turner, G. W.; Valtaoja, E.; Valtonen, M.; Villata, M.; Wagner, S. J.; Webb, J.; Weneit, W.; Wiren, S.
Referencia bibliográfica
Astronomy and Astrophysics Supplement, v.146, p.141-155
Fecha de publicación:
10
2000
Número de citas
71
Número de citas referidas
60
Descripción
We present intensive optical, infrared, and radio monitoring
observations of the BL Lac object OJ 287, taken between the years
1993-1998. Two large optical outbursts were detected at the predicted
times in November 1994 and December 1995. The detection of these
outbursts supports the binary black hole model for OJ 287. Optical and
radio polarisation observations show large variability in the degree of
polarisation and position angle, very similar to those observed during
the 1983/84 outburst in OJ 287. The polarisation position angles show
very similar behaviour during these observations, indicating that, at
least, the magnetic field orientations in radio and optical bands are
related in OJ 287. Optical and infrared light curves show continuous
variability in time scales ranging from tens of minutes to years. In the
radio bands we have observed some of the lowest ever measured flux
levels. During the first optical outburst in November 1994 the observed
radio flux was very low, but during the second optical outburst radio
bands also showed high flux levels. This is a puzzling observation,
which can hopefully be used for discriminating between different
outburst models. On top of the large outbursts OJ 287 has displayed
flaring activity in time scales from days to weeks and shorter time
scale flickering. Based partly on observations made with the Nordic
Optical Telescope, operated on the island of La Palma jointly by
Denmark, Finland, Iceland, Norway and Sweden in the Spanish Observatorio
del Roque de Los Muchachos of the Instituto de Astrofísica de
Canarias. Based partly on observations collected at the German-Spanish
Astronomical Center, Calar Alto, operated by the Max-Planck-Institute
für Astronomie, Heidelberg, jointly with the Spanish National
Commission for Astronomy. Based partly on observations carried out at
Observatorio Astronomico National, San Pedro Martir, Baja California,
Mexico. Based partly on observations made with the IAC-80 Telescope and
the Carlos Sánchez Telescope operated on the island of Tenerife
by the Instituto de Astrofísica de Canarias at the Spanish
Observatorio del Teide.