An optical flare from the quasar PKS 0139-09
ATel #16422; Jennifer Y. Yuan, David M. Russell, D. M. Bramich, Kevin Alabarta (NYU Abu Dhabi)
on 27 Jan 2024; 15:07 UT
Credential Certification: David M. Russell (dave.russell5@gmail.com)
Subjects: Infra-Red, Optical, Gamma Ray, AGN, Black Hole, Blazar, Quasar
PKS 0139-09, also known as OC -065, QSO B0138-097 and 4FGL J0141.4-0928 (Abdollahi et al. 2022, ApJS, 260, 53), is a BL Lac / quasar at redshift z=0.733 (Stocke & Rector 1997, ApJ, 489, 17). Previously, enhanced activity in gamma-ray (E>100MeV) from PKS 0139-09 was detected with the LAT instrument on the Fermi telescope on September 30 and October 1, 2023 (ATel #16266). A near-infrared brightening on November 3, 2023 was also reported from observations taken by Guillermo Haro Observatory, Mexico (ATel #16347).
We carried out optical observations of the source on five separate dates and six sets of observations in total using 1-meter telescopes from the Las Cumbres Observatory (LCO) global telescope network. The LCO images were processed and reduced, and magnitudes were extracted and calibrated using a real-time data analysis pipeline, the "X-ray Binary New Early Warning System" (XB-NEWS; see Russell et al. 2019 and Goodwin et al. 2020 for details).
On 2023-12-01 (MJD = 60279.98), the magnitudes obtained were:
V = 15.85 +/- 0.01, g' = 16.03 +/- 0.01, r' = 15.64 +/- 0.01, i' = 15.32 +/- 0.01;
on 2023-12-07 (MJD = 60285.77), the magnitudes obtained were:
V = 15.56 +/- 0.01, g' = 15.72 +/- 0.01, r' = 15.33 +/- 0.01, i' = 15.03 +/- 0.01;
on 2024-01-04 (MJD = 60313.82), the magnitudes obtained were:
V = 16.26 +/- 0.02, g' = 16.42 +/- 0.01, r' = 16.03 +/- 0.01, i' = 15.73 +/- 0.01;
on 2024-01-06 (MJD = 60315.42), the magnitudes obtained were:
V = 16.31 +/- 0.02, g' = 16.44 +/- 0.02, r' = 16.06 +/- 0.02, i' = 15.79 +/- 0.02.
Throughout just over one month of observations, the optical brightness first increased, then decreased at later dates. Even with the more recent decrease in brightness, PKS 0139-09 is still 1.2 mag brighter than the catalog magnitudes of the source from SDSS DR7 (g' = 17.614 +/- 0.006, r' = 17.242 +/- 0.006, i' = 16.961 +/- 0.006) and 0.2 magnitudes brighter than listed in the Quasars and Active Galactic Nuclei catalog (V = 16.55). By comparing the brightest magnitude on 2023-12-07 to the faintest magnitude on 2024-01-06, the difference for all four bands is remarkably constant: 0.75 for V-band, 0.72 for g'-band, 0.73 for r'-band, and 0.76 for i'-band. This indicates the spectrum of PKS 0139-09 is constant during the flare peak and decay.
Further, multiwavelength observations are encouraged before the flare ends.
This material is based upon work supported by Tamkeen under the NYU Abu Dhabi Research Institute grant CASS (Center for Astrophysics and Space Science).
