Swift follow-up of the flaring high-synchrotron-peaked blazar TXS 1515-273
ATel #12537; F. D'Ammando (INAF-IRA Bologna), S. Cutini (INFN Perugia) on behalf of the Fermi Large Area Collaboration
on 28 Feb 2019; 17:24 UT
Credential Certification: Filippo D'Ammando (dammando@ira.inaf.it)
Subjects: Optical, X-ray, Gamma Ray, >GeV, Request for Observations, AGN, Black Hole, Blazar
Following the gamma-ray flaring activity of the high-synchrotron-peaked blazar TXS 1515-273 detected by Fermi-LAT on 2019 February 24 and 25 (ATel #12532), a Swift target of opportunity observation was performed on February 27.
Swift/XRT data were taken in Photon Counting mode for a total exposure of about 2.5 ksec. The X-ray spectrum (0.3-10 keV) can be fit by an absorbed power law model with an HI column density consistent with the Galactic value in the direction of the source (n_H = 8.5 x 10^20 cm^-2; Kalberla et al. 2005, A&A, 440, 775) and a photon index of 1.9 +/- 0.1. The corresponding observed 2.0-10 keV flux is (10.9 +/- 0.7) x10^-12 erg cm^-2 s^-1. This flux is a factor of 3.5 higher than that observed by Swift/XRT on 2019 January 5, (3.2 +/- 1.2) x10^-12 erg cm^-2 s^-1.
Simultaneous Swift/UVOT observations on 2019 February 27 found TXS 1515-273 about 0.7 mag brighter in U band (U = 15.89 +/- 0.07) compared to the UVOT observations performed on January 5 (U = 16.56 +/- 0.07).
In consideration of the ongoing activity of this source, confirmed also by the Swift observations, we strongly encourage further multiwavelength observations. For this source the Fermi-LAT contact persons is S. Cutini (sara.cutini@pg.infn.it).
We would like to thank the Swift Team for making these observations possible, in particular B. Sbarufatti as Swift Observatory Duty Scientist.
