AGILE detection of the flaring gamma-ray blazar PKS 1510-089

ATel #1957; F. D'Ammando (Univ. Tor Vergata and INAF-IASF Roma), S. Vercellone (INAF-IASF Palermo), M. Tavani, G. Pucella (INAF-IASF Roma), A. Chen, A. Giuliani (INAF-IASF Milano), A. Bulgarelli (INAF-IASF Bologna), G. Piano, V. Vittorini, E. Costa, M. Feroci, I. Donnarumma, L. Pacciani, E. Del Monte, F. Lazzarotto, P. Soffitta, Y. Evangelista, I. Lapshov, M. Rapisarda, A. Argan, A. Trois, G. De Paris (INAF-IASF Roma), M. Marisaldi, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Galli (INAF-IASF Bologna), P. Caraveo, S. Mereghetti, F. Perotti, M. Fiorini, A. Zambra (INAF-IASF Milano), A. Pellizzoni, M. Pilia (INAF-OACagliari), G. Barbiellini, F. Longo, E. Moretti, E. Vallazza (INFN Trieste), P. Picozza, A. Morselli, S. Sabatini (INFN Roma-2), M. Prest (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P. Cattaneo (INFN Pavia), C. Pittori, F. Verrecchia, P. Santolamazza, S. Colafrancesco, P. Giommi (ASDC), L. Salotti (ASI)
on 10 Mar 2009; 12:14 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Marco Tavani (tavani@iasf-roma.inaf.it)

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During the current AGILE pointing centered near the Galactic Center the Gamma-Ray Imaging Detector (GRID) has detected significant gamma-ray emission above 100 MeV from a source positionally consistent with the blazar PKS 1510-089 (Position J2000.0: RA=15h12m50.5329s, DEC=-09d05m59.828s, redshift z = 0.361).

The source positional error box is centered at Galactic coordinates l = 351.15 deg, b = 40.02 deg with a radius of about 0.5 degrees and it is consistent with the source 1AGL J1511-0809 in the First AGILE Catalogue, identified with PKS 1510-089. This object is classified as a Flat Spectrum Radio Quasar (FSRQ) and was already known as an EGRET gamma-ray source, 3EG J1512-0849. Moreover this source was previously well detected during gamma-ray flares both by AGILE (Bulgarelli et al., ATel #1199; D'Ammando et al., ATel #1436; Pucella et al. 2008, A&A, 491, L21) and Fermi-LAT (Tramacere, ATel #1743, Ciprini et al., ATel #1897).

Preliminary analysis indicates that the source shows a significant increase of the gamma-ray activity starting on 8 March 2009 and a maximum likelihood analysis of the AGILE-GRID data obtained between 2009-03-08 14:00 UT and 2009-03-10 4:00 UT for photon energies above 100 MeV results in a detection significance of above 5 sigma with a source flux in excess of 200 x 10^-8 ph cm^-2 s^-1.

A preliminary analysis of the Super-AGILE data over the same time period and the same sky region does not show any counterpart in the 20-60 keV energy range, with a 3-sigma upper limit of 50 mCrab on the average flux. The AGILE monitoring of the field containing this source will continue until 2009-03-25. We strongly encourage multi-frequency observations of PKS 1510-089 during this gamma-ray high state.