Swift observations of the flaring GeV blazar OG 050 (TXS 0529+075)
ATel #3773; S. Ciprini, D. Gasparrini, F. Verrecchia, S. Cutini (ASI Science Data Center, Italy), on behalf of the Fermi Large Area Telescope Collaboration and J. A. Kennea (Dep. of Astronomy and Astrophysics, Penn State University, State College, PA, USA)
on 19 Nov 2011; 12:03 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@pg.infn.it)
Subjects: Optical, Ultra-Violet, X-ray, AGN, Blazar, Quasar
Following the reported flaring activity of the flat spectrum radio quasar OG
050 (TXS 0529+075, z=1.254) in the GeV energy band (ATel#3750)
Swift ToO observations were requested and performed on 2011 Nov. 11 and Nov. 15,
when the source was still in an active gamma-ray state. Swift XRT data were
taken in photon counting mode for a net exposure of about 3ksec for both the
observations.
For the Nov. 11 observation the X-ray spectrum can be fit by an
absorbed power law with the HI column density fixed to the Galactic value of
N_HI = 1.7 x 10^21 cm^-2 (Kalberla et al. 2005, A&A, 440, 775) and a photon
index of 1.0+/-0.2. The unabsorbed 0.3-10 keV flux is (4.4+/-1.1) x10^-12 erg
cm^-2 s^-1, which is a factor of about 3 higher than that previously detected by
XRT on 2008 Aug. 4 in a similar (4ksec) observation.
For the Nov. 15 observation the X-ray spectrum can be fit by an absorbed
power law (with HI column density fixed to the same value of Nov.11) and a
photon index of 1.3+/-0.2. The unabsorbed 0.3-10 keV flux is (3.8+/-1.2) x10^-12
erg cm^-2 s^-1, which is a factor of about 2.5 higher than that previously
detected by XRT on 2008 Aug. 4.
Swift UVOT found OG 050 at dereddened U=15.10 +/-0.04 (statistical only) on
Nov. 11, and at dereddened U=16.55 +/-0.04 (statistical only) on Nov. 15,
that is about a factor 2.3 mag and about a factor 0.8 mag respectively
brighter than the archival observation of 2008 Aug. 4.
Synergetic Fermi-Swift observations of simultaneous high brightness states at
GeV, X-ray and UV energy bands on Nov.11 confirm identification of the flaring
gamma-ray source with the flat spectrum radio quasar OG 050.
We thank the Swift Team and the Observation Duty Scientists (ODS) for
the rapid scheduling of this observation.
