OJ 287  2005-2008 Project - Introduction

The BL Lac object OJ 287 is the only known extragalactic source showing convincing evidence of a major periodical component  in its optical emission. OJ 287 is also one of the best observed BL Lac objects: observations date back for over 100 years.  This historical light curve shows several large major outbursts, that occur every 11-12 years with a double peak structure. The last outburst was monitored with the OJ94 project (period 1993-1997). The next outburst (the first of this new millennium) is expected to occur in period 2005-2007. According to the precessing binary black hole model, the first outburst of the season occurred in Nov.2005, as optical data collected during the multiwavelenght XMM-campaign seems to confirm, and the second one is expected in Sept.9, 2007 if the precession rate is 37.5 degrees per period, in Sept.16, 2007 if the precession rate is 39.1 degrees per period. Both precession rates can be supported by the historical light curve. If the precession is not relativistic, and there is no loss of energy to gravitational radiation, the outburst will begin Oct.8, 2007. In this model, the fall of 2006 is a unique opportunity to observe OJ287 in its low state. OJ287 will not be as dim as it is this fall for another 40 years.
A long-term optical-radio campaign started in late 2004 and will cover the period 2005-2008 (MMVI means 2006 in roman numbers). The required optical sampling is moderate in the non-outburst phases: at least 1 or 2 data-points per band per week in the optical band (priority to R-band filter). The plan is for a regular monitoring of OJ 287 continuing until May 2008.
The teams of the ENIGMA EC Research Training Network are contributing to this long-term monitoring (as a long-term ENIGMA-Campaign). All the observatories (radio, optical, infrared) interested in the campaign may add  OJ 287 to their telescope schedules. An archive of the data obtained is planned to be constructed during the project. Regularly updated optical data from a photometric-polarimetry monitoring programme     (led by J. Heidt and K. Nilsson) can be previewed.

During these years additional shorter-duration and intensive-sampling multiwavelength campaigns will be carried out in several occasions (e.g. flares, high-energy satellite and large telescope observations, intranight campaigns, etc.).  Announcement and information about these short specific campaigns will be advertised in this web page. Each intensive MW campaign will be under the responsibility of a different person, to handle faster the data and publications.  

This strategy will allow to cover a large range of variability timescales and a large range  of electromagnetic frequencies, with relevant physical predictions on the key blazar OJ 287 and AGN in general.

NEW: a 4th exciting XMM-Newton observation of OJ 287 (April 22, 2008): the XMM Newton observation is scheduled in April 22, 2008, (starting at 16:56  UT,  revolution: 1533) -  (S.Ciprini). Radio-optical observations in April till the end of the the current nigth-optical season for the object are very welcome! Intensive optical intra-day follow up around the pointing date (April 22, see below) is recommended.

	Wide Multifrequency Suzaku-MAGIC-Swift campaign on OJ 287 (November 2007).    Suzaku X-ray satellite observations (N.Isobe, M.Hayashida): start: 2007, Nov.07, - 11:13:00 UT stop: 2007, Nov.09, - 21:30:00 UT ----- MAGIC ToO gamma-ray observations scheduled in November 2007 (M.Hayashida, E.Lindfors, A.Sillanpää). -----     Swift UV/X-ray satellite ToO short  (2ks per exposure) monitoring (i.e. repeated) observations scheduled from Nov.7 to Nov.23, 2007 every day (A.Stamerra, N. Gehrels). -----    Daily observations by the WEBT consortium partners are invited in November 2007 (with intensive intra-day follow-up observations during the Suzaku pointings). Official WEBT e-mail announcement will/can follow.
	Optical long-term photometry-polarimetry programme web page.
	Suzaku X-ray satellite observations of OJ 287 performed in April 10-13, 2007. MAGIC ToO pointings performed (April 09-13, 2007, from beginning of dark night to zenith angle = 35 deg.). Some radio-optical observations executed.
	A 3rd XMM-Newton observation (48ksec, ~13h) performed on Nov.17, 2006 joint with ground-based coordinated radio-optical observations. XMM observation carried out without relevant problems.
	Single dish 3mm polarimetric measurements made with the IRAM 30m mm-telescope on Nov.12,17,18,2006. VLBA 7mm and 1.2 cm radio-structure polarimetric-astrometric observations succesfuly performed on Nov.16, 2006.
	2 XMM-Newton observations of OJ 287 and WEBT coordinated campaign (Apr. & Nov.2005)
	Finding chart and comparison optical-near-IR photometric sequence
	Tuorla monitoring light curves of blazars
	The past "OJ94" project (1993-1998)  - Project logo
	OJ 287 bibliography/information:  - by ADS-NASA   - by NED   - by Simbad   - by Google

Schedules and status of the OJ 287 observations*

(* information below can be incomplete and/or no regularly updated) 

	Long-term monitoring observations 2005-2008 (ENIGMA network and who want to join) started in autumn 2004. Recommended sampling: at least 1 data point per filter/band per week (priority 1 R-band data point per week, with possible regular monitoring, see details below). This 2006-2007 season is an important period and the observations can be increased.
	CalarAlto and NOT  photometry and polarimetry long-term programme (J. Heidt, K. Nilsson)
	Suzaku X-ray satellite observations in Nov.07-09, 2007 (N.Isobe, M.Hayashida). -- MAGIC ToO gamma-ray observations in Nov. 2007 (M.Hayashida, E.Lindfors, A.Sillanpää). --  Swift UV/X-ray satellite ToO short-exposure monitoring observation in the period Nov.07-23, 2007 (A.Stamerra, N. Gehrels). -- Observations by the WEBT consortium invited in Nov.2007.
	MAGIC ToO observations scheduled on Apr.09-13, 2007 joint with Suzaku X-ray satellite pointing on Apr.10-13, 2007 (M. Hayashida, E. Lindfors, A. Sillanpää)
	Swift satellite ToO short (4 Ksec) perormed on (Nov.16,17,18, M. Kadler, N. Gehrels).
	MAGIC ToO observations simultaneous to the 3rd XMM-pointing performed (Nov.17, D. Kranich). - MAGIC ToO observations performed already in Nov. 2005 (E. Lindfors), and 10h (normal-schedule) in Jan.2005.
	Single dish 3mm polarimetric measurements made with the IRAM 30m mm-telescope on Nov.12,17,18,2006. VLBA 7mm and 1.2 cm radio-structure polarimetric-astrometric observations succesfuly performed on Nov.16, 2006 (I. Agudo, T. Krichbaum).
	Intensive intra-night observations at NOT (Feb.1 2005): lost due to bad weather (K. Nilsson).
	VLBA radio-structure/polarization observations in 5 bands: 6 times, 8h for the period 2005-2006  (T. Savolainen). More observations planned in the period 2007-2008.
	ESO VLT detailed spectroscopic observation performed (ESO Period 75, K. Nilsson).
	VLBA and global 3mm-VLBI radio-mm-structure/polarization observations on 2 and 17 April 2005, (I. Agudo).
	XMM-Newton X-ray observations: 2 pointings (about 40 ksec each), on 12 April 2005 and Nov. 3-4, 2005 (Cycle AO-4, S. Ciprini).
	A third XMM-Newton pointing (about 43ksec) performed in Nov.17, 2006  (Cycle AO-5, S.Ciprini).
	NEW: a 4th XMM-Newton observation foreseen in a day of the week 2008, April 20-26 (revolutions: 1532-1535).
	ToO single-dish Effelsberg 100m flux/polarization observations during the Apr.12 and Nov.8-9-10, 2005, 12h per day (ToO, L. Fuhrmann).
	4 sessions of Global 3mm-VLBI observations awarded in period Oct.2005-Apr.2007 (E. Rastorgueva, K. Wiik).
	ToO observations by MAGIC performed in Nov.1-4 and Nov. 10-13 (E. Lindfors).

Preliminary R-band optical light curve during the XMM-Newton and WEBT MW campaign (plus the extended 2005-06 campaign).	Preliminary summary of near-IR and multiband optical light curves during the campaign.

Observing strategy of OJ 287 

Optical Strategy and Data Reduction:
   
Long-term strategy: the accent is on a continuous and regular monitoring, without large and irregular gaps empty of data, rather than on intense one. The ideal situation would be to have at least a sequence of Johnson's UBV and Cousins' RI data point per week per observatory and 2-3 R data point per week during most of the campaign duration. The priority is to have one Cousins' R-filter data point per week at least (also integrating/averaging 3,5 frames). R-band only observations are recommended to small telescopes (< 50cm), while 1-2 UBVRI sequences per week to larger telescopes.  For mid-latitude observers in the northern hemisphere the OJ 287 optical observing season is between October and May.  
   
Intensive campaigns strategy: usually performed around the observation epoch of a satellite or large telescope, or during a relevant flaring, or other occasions. Data will be collected as instrumental magnitudes of the source and reference stars, in order to apply the same analysis and calibration procedures to all datasets. The suggested data format for instrumental magnitudes is in separated tables for each filter with rows as in the example below: 

where JD (or equivalent date + UT) must be geocentric at mid exposure. Times are requested with second precision (e.g. 2003 10 01 00 00 01, or the preferred corresponding JD - 2452000 = 913.50001 with five decimal digits); mags and errors should have three decimal digits. Observers are requested to perform bias/dark correction and flat-fielding on their frames, and to obtain the instrumental mags with some procedure. Both aperture photometry (possibly using IRAF or CCDPHOT) or Gaussian fitting are allowed. In the case of aperture photometry, we suggest that all observers use the same parameters, i.e. 8, 13, and 18 arcsec for the radii of the aperture and of the edges of the sky annulus. However, the sky annulus radii can be seeing-dependent in order not to contaminate the sky region with source flux.
    
Observer are strongly encouraged to submit their data in the exact format above described, in order to make the calibration procedure more efficient and the analysis faster.
    
OJ 287 is a pure BL Lac object, therefore optical polarization measurements are very important too.
   
   
Near-IR Observations
Observers having access to infrared telescope facilities, are invited to contribute with infrared observations inn the same way specified for the optical strategy. Our finding chart + magnitude table also contains the J, H, K mag of comparison stars adopted. 
    
   
Radio Observations
During the campaign multiband radio flux (priority) and polarization measures are important. For the long-term campaign  2005-2008 weekly observations are suitable. For intensive-campaigns the strategy is the same mentioned above for the optical observers. 

Contacts
All observers interested in participating in long-term observations are invited to send a message to the managers of the long-term monitoring projects (alphabetical order):

- J. Heidt: jheidt<at>lsw.uni-heidelberg.de
- K. Nilsson: kani<at>utu.fi
- A. Sillanpää: aimosill<at>utu.fi
- L.O. Takalo: takalo<at>utu.fi