Swift follow-up of the flaring blazar OJ 248

ATel #4440; F. D'Ammando (Univ. Perugia, INFN), and M. Orienti (Univ. Bologna, INAF-IRA Bologna) on behalf of the Fermi Large Area Telescope Collaboration
on 1 Oct 2012; 09:15 UT
Credential Certification: Filippo D'Ammando (filippo.dammando@fisica.unipg.it)

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Following the gamma-ray flaring activity of the flat spectrum radio quasar OJ 248 (also known as 2FGL J0830.5+2407, Nolan et al. 2012, ApJS, 199, 31) detected by Fermi LAT starting from 2012 September 23 (ATel #4421) a Swift target of opportunity observation was performed on September 28.

Swift/XRT data were taken in Photon Counting mode for a total exposure of about 4.0 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 = 2.9 x 10^20 cm^-2, Kalberla et al. 2005, A&A, 440, 775) and a photon index of 1.5+/-0.1. The corresponding observed 0.3-10 keV flux is (10.1+/-0.8) x10^-12 erg cm^-2 s^-1. This flux is about a factor of 5 higher than that observed by Swift/XRT on 2012 March 30, (1.8+/-0.7) x10^-12 erg cm^-2 s^-1, with a photon index of 1.8+/-0.4. Taking into consideration the Swift/XRT observations performed during 2008-2012, OJ 248 on 2012 September 28 reached the highest count rate in the 0.3-10 keV energy range (see http://www.swift.psu.edu/monitoring/source.php?source=QSOB0827+243 ) .

Simultaneous Swift/UVOT observations on 2012 September 28 found OJ 248 about 0.7 mag brighter in U-band (U = 15.93+/-0.06), 0.4 mag brighter in W1-band (W1 = 15.96+/-0.07), and 0.3 mag brighter in W2-band (W2 = 16.20+/-0.06) compared to the UVOT observations performed on 2012 March 30.

Swift observations confirmed the ongoing high activity of OJ 248. Further multiwavelength observations are encouraged. For this source the Fermi LAT contact person is M. Orienti (orienti@ira.inaf.it).

We would like to thank the Swift Team for making these observations possible.