Enhanced activity of OJ 287 after its emergence from Swift Sun constraint
ATel #12086; S. Komossa (MPIfR), D. Grupe (Morehead State Univ.), J. L. Gomez (Inst. de Astrofisica de Anadalucia)
on 8 Oct 2018; 19:30 UT
Credential Certification: St. Komossa (stefanie.komossa@gmx.de)
Subjects: Optical, Ultra-Violet, X-ray, AGN, Blazar
We have observed the blazar OJ 287 which has emerged after being Sun constrained for
~100 days with the Neil Gehrels Swift observatory. Between 2018 September 26 and October 6 it showed
enhanced activity at all wavebands in comparison to its last Swift observation on 2018 June 12.
On 2018 September 26, its UVOT W2 magnitude was at 14.58 +/- 0.04 (corrected for Galactic reddening,
or a flux level of (1.51+/-0.04)e-11 erg/cm2/s), which is 0.25 magnitudes brighter
than during its last Swift observation, and the brightest level since February 2018.
Other optical/UV magnitudes on 26 September were UVM2: 14.57+/-0.04 (14.33), UVW1: 14.62+/-0.04
(14.45), U: 14.50+/-0.04 (14.37), B: 15.37+/-0.04 (15.26), V: 15.03+/-0.05 (14.95)
(uncorrected and corrected for Galactic reddening, respectively).
In X-rays, OJ 287 on September 26 was detected at a countrate of 0.33 +/- 0.02 counts/s in
the 0.3-10 keV band, 30% higher than during the observation
on 2018 June 12. Fitting a single powerlaw with absorption fixed to the Galactic value gives a photon
index Gamma_x = 2.27 +/- 0.15, and an absorbed X-ray flux in the observed (0.3-10) keV band of
1.1e-11 erg/cm2/s.
OJ 287 has shown repeated periods of high activity since its December 2015 outburst
(e.g., ATEL #8378, ATEL #8372, ATEL #8411). Its current level of activity is well below
the highest states observed in 2016-2017 (e.g., ATEL #9629, ATEL #9650, ATEL #9709, ATEL #10043).
We have followed OJ 287 with Swift since December 2015 and found peak values of 1.9 cts/s in
X-ray countrate in February 2017 and 12.82 in UVW2 magnitude (corrected for extinction) in
October 2016.
