Swift follow-up of the AGN PKS 0521-36 during a high gamma-ray activity state
ATel #12808; F. D'Ammando (INAF-IRA Bologna)
on 27 May 2019; 09:48 UT
Credential Certification: Filippo D'Ammando (dammando@ira.inaf.it)
Subjects: Infra-Red, Optical, Ultra-Violet, X-ray, Gamma Ray, Request for Observations, AGN, Black Hole, Blazar, Quasar
Following a recent high gamma-ray activity of the AGN PKS 0521-36 detected by Fermi/LAT (Fermi/LAT Monitored Source List Light Curves), we performed a Swift target of opportunity observation on 2019 May 25.
Swift/XRT data were taken in Photon Counting mode for a total exposure of 2.1 ksec. The X-ray spectrum (0.3-10 keV) can be fit by an absorbed power law model with a HI column density consistent with the Galactic value in the direction of the source (n_H = 3.58 x10^20 cm^-2, Kalberla et al. 2005) and a photon index of 1.35 +/- 0.08. The corresponding observed 2.0-10 keV flux is (2.45+/-0.16) x10^-11 erg cm^-2 s^-1, comparable to the highest X-ray flux observed during the period 1999-2012 (D'Ammando et al. 2015, MNRAS, 450, 3975).
Simultaneous Swift/UVOT observations were performed on 2019 May 25. The measured magnitudes are V = 14.31 +/- 0.04, B = 14.90 +/- 0.05, U = 14.27 +/- 0.05, W1 = 14.14 +/- 0.06, M2 = 14.26 +/-0.06, W2 = 14.31 +/- 0.06, about 0.2-0.3 mag brighter in all bands compared to the peak values observed during 2005-2012. This confirms the high activity state of the source also in optical and UV.
In consideration of the ongoing activity of this source, confirmed also by the Swift observations, we strongly encourage further multiwavelength observations.
We would like to thank the Swift Team for making these observations possible, in particular N. J. Klingler as the Swift Observatory Duty Scientist.
