FERMI /LARGE AREA TELESCOPE DISCOVERY OF GAMMA-RAY EMISSION FROM THE FLAT-SPECTRUM RADIO QUASAR PKS 1454–354
Abdo, A. A. AA ; Ackermann, M. ; Atwood, W. B. ; Cavazzuti, E. ; Colafrancesco, S. ;
May - 2009
ISSN : 0004-637X ;
journal : The Astrophysical Journal

Issue : 1
type: Article Journal

Abstract
We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope of high-energy ³-ray (GeV) emission from the flat-spectrum radio quasar PKS 1454354 (z = 1.424). On 2008 September 4, the source rose to a peak flux of (3.5 ± 0.7) × 106 ph cm2 s1 (E > 100 MeV) on a timescale of hours and then slowly dropped over the following 2 days. No significant spectral changes occurred during the flare. Fermi/LAT observations also showed that PKS 1454354 is the most probable counterpart of the unidentified EGRET source 3EG J15003509. Multiwavelength measurements performed during the following days (7 September with Swift; 6-7 September with the ground-based optical telescope Automated Telescope for Optical Monitoring; 13 September with the Australia Telescope Compact Array) resulted in radio, optical, UV, and X-ray fluxes greater than archival data, confirming the activity of PKS 1454354.

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publication available also here:
http://iopscience.iop.org/0004-637X/697/1/934