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Swift detection of an X-ray flare from the flaring blazar PKS 0502+049

ATel #4905; Roopesh Ojha (NASA/GSFC) and Michael Dutka (CUA) on behalf of the Fermi Large Area Telescope Collaboration and Katja Pottschmidt (CRESST-UMBC/NASA-GSFC) and Felicia Krauss (ECAP/FAU Erlangen/Univ. Wuerzburg)
on 21 Mar 2013; 19:14 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

Subjects: Ultra-Violet, X-ray, AGN, Black Hole, Blazar, Quasar

Referred to by ATel #: 6425

Following the recent gamma-ray flaring activity of the flat spectrum radio quasar PKS 0502+049 (also known as 2FGL J0505.5+0501, Nolan et al. 2012, ApJS, 199, 31), detected by Fermi LAT on 2013 March 2 (ATel#4858), a Swift target of opportunity observation was performed on March 13.

Swift/XRT data were taken in Photon Counting mode for a total exposure of about 3.5 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 = 8.8 x 10^20 cm^-2, Kalberla et al. 2005, A&A, 440, 775) and a photon index of 1.7+/-0.5. The corresponding unabsorbed 0.3-10 keV flux is (1.9+/-0.4) x10^-12 erg cm^-2 s^-1. This flux is more than twice as high as that observed by Swift/XRT on 2009 January 19, (0.7+/-0.2) x10^-12 erg cm^-2 s^-1, with a photon index of 1.5+/-0.5.

Simultaneous Swift/UVOT observations (corrected for extinction) show a U-band magnitude (Swift Vega system) = 17.52+/-0.13, while only a 3-sigma upper limit of U > 17.1 has been obtained on 2009 January 19.

Further multiwavelength observations are encouraged. For this source the Fermi LAT contact person is Roopesh Ojha (Roopesh.Ojha@gmail.com).

We would like to thank the Swift Team for making these observations possible, in particular Christopher Mountford as the Swift Observatory Duty Scientist.