Frankfurt Quasar Monitoring

OJ 287
Object data

  Cross-Identifications   PG 0851+202, PKS 0851+202, VRO 20.08.01
  GC 0851+20, B2 0852+20, IRAS 08519+2017
  1ES 0851+203, RX J0854.8+2006, 0851+202
  SDSS J085448.87+200630.7, 3EG J0853+1941
  2MASX J08544889+2006307, VSOP J0854+2006
  QSO J0854+2006, QSO B0851+202, OJ +287
  1RXS J085451.5+200646, RGB J0854+201
  Equat. coordinates   RA  08 54 48.8     DE  +20 06 30     (J2000)
  Constellation   Cancer
  Type   BL Lac
  Redshift (1)   z=0.306
  Distance (2) (3)   1176 Mpc
  Total mag range (mv) (4)   12.0 - 17.5
  Catalog Magnitude (1)   15.43
  Absolute Magnitude (1)   -25.5 MB
  Light Travel-Time (2)   3.357 × 109 yrs
(1) Véron-Cetty & Véron 2006, A&A 455, 776
(2) NASA/IPAC Extragalactic Database
(3) Co-Moving Radial Distance
(4) Literature

Finding chart

Comparison stars

star  B V Rc Ic
A 14.6102 13.9862 13.6362 13.2932
--- 14.181 13.741 13.281
C --- 14.601 14.341 14.031
D --- 14.941 14.651 14.321
E 15.8912 15.2032 14.7982 14.4082
F --- 15.3822 15.0332 ---
G --- 15.881 15.501 15.081
H --- 16.121 15.661 15.211
K 17.2092 16.5412 16.1342 15.7342
L 18.4972 17.0622 16.0892 15.0822
(1) comparison stars from Fiorucci et al. 1996, A&AS, 116, 403
(2) comparison stars from Gonzàlez-Pérez et al. 2001, AJ, 122, 2055

Colour chart
Credit: SDSS  /  Size 13´× 13´ /  Chart by S. Karge

Light curve

OJ 287 is a violently variable BL Lac object in Cancer and is also one of the best-studied objects of its kind. This BL Lac object displays extremely large and rapid flux variations at both radio and optical wavelengths with variability time-scales varying from minutes to years - a typical OVV. OJ 287 is very active with a total optical variability of more than 5 mag, showing large optical outbursts. Together with its high degree of polarization, this object was classified as a BL Lac object. The designation OJ 287 derives from the radio survey of the Ohio State University (OJ), where this object was cataloged as a radio source. Initially, the radio source was discovered in the mid 1960s by both the Vermillion River Observatory radio survey (VRO) at 610.5 MHz and the Ohio radio survey (OJ) at 1415 MHz.

The most interesting feature about OJ 287 is its optical behaviour. Light curves of former monitoring programmes revealed outbursts with a period of approximately 12 years in the optical and in the infrared. Each outburst is described by a twin-peak structure. This unusual periodicity is explained by the model of a precessing binary black hole, consisting of two supermassive black holes with 18×109 solar masses for the primary and 1.5×108 solar masses for the secondary black hole. According to this model, the secondary black hole is moving around the primary on a highly eccentric orbit, perturbing the accretion disk of the primary during pericenter passages, once every 12 year orbital cycle. International multi-wavelength monitoring programmes during the predicted outbursts in 1993/94 (OJ-94 project) and 2005/07 confirmed this model. The author participated in the 2005/07 Pro-Am observing campaign.
The latest predicted outburst of OJ 287 occured in November–December 2015, coinciding with the centenary of General Relativity.
In the case of OJ 287, the tremendous gravitational field of the larger black hole causes the smaller black hole’s orbit to precess at an incredible 39° each orbit, as predicted by Einstein’s theory of general relativity.
"Its (OJ 287) light curve is definitely not periodic but the deviations from periodicity are systematic and predictable in a model that contains a gravitational wave driven inspiralling spinning binary black hole system as its central engine" (Valtonen et al. 2016).
Due to the loss of orbital energy by gravitational radiation
the two black holes will merge within the next 10,000 years.

For both visual and CCD observers, OJ 287 is an interesting target at any time. During brighter state, visual observers with telescopes of 8- to 10-inch of aperture and larger will have no difficulties to spot this blazar. Visually, OJ 287 remains a stellar object even with large apertures. CCD observers as well as visual observers may use the comparison stars given above. Other photometric sequences were published by Penston et al. (1973), Craine et al. (1975), Veron et al. (1975), McGimsey et al. (1976), Smith et al. (1985), and the BAAVSS - which underlines the high astrophysical interest regarding this very special AGN.

Observers who like to continue their observing session with more quasi-stellar photons may turn to
quasar PG 0844+349, a bright 14-mag object at a distance of about 0.8×109 light-years, located some 14° N of OJ 287.
Another violently variable BL Lac object is
PKS 0754+100, which lies some 17.3° SW of OJ 287, at a distance of about 3×109 light-years.

When you are around for OJ 287 with your telescope, do not forget to visit open cluster M44, the "beehive cluster", about 3° E of OJ 287. Some 1.6° to the SW you find the interacting galaxy pair NGC 2672/73 (Arp 167).
Variable star observers may like to take a look at carbon star T Cnc (var. 7.6-10.5 mag), only 30´SE of OJ 287. Its vivid reddish c
olour is a nice catch for medium sized telescopes.

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Landessternwarte Heidelberg

Hamburg Quasar Monitoring


Gary Poyner (light curve)

Sloan Digital Sky Survey

© Stefan Karge (FQM)  /  last obs. 2024-05-22