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
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.
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.
||XMM Obs: Start
||2008-04-22 at 16:56 UT
||2008-04-23 at 08:44 UT
Suzaku-MAGIC-Swift campaign on OJ 287 (November 2007).
X-ray satellite observations (N.Isobe, M.Hayashida):
start: 2007, Nov.07, - 11:13:00 UT
stop: 2007, Nov.09, - 21:30:00 UT
ToO gamma-ray observations scheduled in November 2007 (M.Hayashida,
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.
long-term photometry-polarimetry programme web page.
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
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.
XMM-Newton observations of OJ 287 and WEBT coordinated
campaign (Apr. & Nov.2005)
chart and comparison optical-near-IR photometric sequence
monitoring light curves of blazars
past "OJ94" project (1993-1998) - Project
bibliography/information: - by
ADS-NASA - by
NED - by
Simbad - by
Schedules and status of the OJ 287 observations*
(* information below can be incomplete and/or no
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.
photometry and polarimetry long-term programme (J. Heidt, K.
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.
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)
satellite ToO short (4 Ksec) perormed on (Nov.16,17,18, M.
Kadler, N. Gehrels).
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).
intra-night observations at NOT
(Feb.1 2005): lost due to bad weather (K. Nilsson).
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.
detailed spectroscopic observation performed (ESO Period 75,
and global 3mm-VLBI
radio-mm-structure/polarization observations on 2 and 17
April 2005, (I. Agudo).
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
||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
observations awarded in period Oct.2005-Apr.2007 (E.
Rastorgueva, K. Wiik).
||ToO observations by
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
Observing strategy of OJ 287
Optical Strategy and Data
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
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.
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
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.
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
- 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