2 OJ-94 project

The OJ-94 project was set up at a meeting in Seili, Finland, July 1993. This meeting was attended by eight astronomers, who have later formed the key members of the project (see Takalo 1996). The plan was to apply for the International ITP-time on the Canary Island Telescopes in order to confirm the predicted optical outburst in blazar OJ 287 and to collect extensive monitoring observations. It was also decided then that in addition to OJ 287 we will include 3C 66A, AO 0235+164 and S5 0716+714 as objects to be observed. The main goal in this was to use the observations of these objects as control observations for OJ 287, in order to study and understand various instrumental effects. All these objects are BL Lac objects, with similar characteristics as OJ 287. Especially in 3C 66A we had not seen any short time scale (hours) variability in the infrared monitoring at the Carlos Sanchez Telescope (Takalo et al. 1992) and nor had it shown any large variability in optical bands (see Takalo et al. 1996). This strategy for the control objects, failed partly because all these objects showed large variability during the project observations (e.g. Takalo et al. 1996, 1998, 1999).

Figure 1: The historical light curve of OJ 287 with the new data, showing the large optical outbursts with the 11.86 year period

The first observations in the OJ-94 Project were taken during autumn 1993. We also received the ITP-time at the Canary Island Telescopes for the project for half a year, during winter 1993/94. During the ITP-time the project receives 5% of the observing time on these telescopes. Since we were interested in detailed long term light curves of these objects we asked colleagues around the world, to join us in monitoring these objects. We were very succesful in this. Today there are over 60 astronomers from 11 different countries in the project. During these last six years we have collected over 10000 data points on OJ 287, and about 7000 on 3C 66A. These data sets constitute the best ever observed optical light curves on any extragalactic objects. Besides optical observations we have also infrared and radio monitoring data, and some UV, X-ray, and gamma-ray data on OJ 287.

During the project we have held yearly project meetings, in which the project observations and results have been discussed. After the meeting in Seili, meetings have been held at Orilampi, Finland (1994), Oxford, UK (1995), Girona, Spain (1996), Perugia, Italy (1997), Turku, Finland (1998), and Torino, Italy (1999). Presentations given in some of these meetings have been published in a series of books (Kidger & Takalo 1994; Takalo 1996; Tosti & Takalo 1998; Raiteri et al. 1999). These meetings have been very productive and informative in discussing the current status of the OJ-94 project and blazar monitoring campaigns as a whole. The OJ-94 Project is still in operation and will continue to the next expected outburst of OJ 287 in 2006/07; furthermore the monitoring has been extended to some other bright blazars. This project has strongly increased the collaborations between different monitoring groups. We invite other observing groups to collaborate in this project.

 

Table 1: Observatories and instruments used during the 1993-1998 monitoring. Pol = Photopolarimetric and Phot = Photometric observations with a photometer

Telescope	Size	Inst.	Filters
Nordic Optical Telescope	2.5 m	CCD	BVRI
		Pol.	UBVRI
Jacobus Kapteyn Telescope	1.0 m	CCD	UBVRI
Heidelberg	70 cm	CCD	R
Torino Observatory	1.05 m	CCD	BVR
Tuorla Observatory	1.03 m	CCD	V
Calar Alto	1.2/2.2 m	CCD	UBVRI
Boltwood	17 cm	CCD	VRI
IAC-80	82 cm	CCD	BVRI
Capilla Peak Observatory	61 cm	CCD	BVRI
Cananea	2.2 m	CCD	R
Lowell Observatory	1.06 m	CCD	BVRI
Rome	50 cm	CCD	BVRI
Crimea Observatory	1.25 m	Pol.	UBVRI
San Pedro Martir	2.1/1.5 m	CCD	BVRI
RoboScope	41cm	CCD	V
Perugia Observatory	40 cm	CCD	VRI
Abastumani Observatory	70 cm	CCD	VRI
Carlos Sánchez Telescope	1.5 m	Phot	JHK
UKIRT	3.8 m	Phot	JHK
Michigan Radio Telescope	26 m	Cont.	4.8,8,14 GHz
Metsähovi Radio Telescope	14 m	Cont.	22, 37 GHz
SEST	15m	Cont.	90, 230 GHz