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AGILE gamma-ray detection of a strongly variable source in the Cygnus region

ATel #1308; A. Chen, S. Vercellone, A. Giuliani, S. Mereghetti, A. Pellizzoni, F. Perotti, F. Fornari, M. Fiorini, P. Caraveo, A. Zambra (INAF/IASF Milano), A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Marisaldi, M. Galli, (INAF/IASF Bologna), M. Tavani, G. Pucella, F. D'Ammando, 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), G. Barbiellini, F. Longo (INFN Trieste), P. Picozza, A. Morselli (INFN Roma-2), M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), F. Mauri (INFN Pavia) and P. Giommi, C. Pittori, L. A. Antonelli, D. Gasparrini, S. Cutini, F. Verrecchia (ASDC) and L. Salotti (ASI)
on 27 Nov 2007; 19:19 UT
Credential Certification: Andrew Chen (chen@iasf-milano.inaf.it)

Subjects: Gamma Ray, >GeV, Transient

Referred to by ATel #: 1313, 1320

The AGILE satellite, currently in its Science Verification Phase, during the Observing Block that started on 2007-11-02 12:00 UT, detected significant and strongly variable gamma-ray emission from the Cygnus region lasting only about 1 day.

The variable source positional error box is centered at Galactic coordinates l = 75.0 deg, b = -0.4 deg, and has a radius of about 1 degree.

A preliminary maximum likelihood analysis of the AGILE-GRID (Gamma-Ray Imaging Detector) data obtained between 2007-11-23 03:58:55 and 2007-11-24 03:58:55 for photon energies above 100 MeV results in a detection significance of over 5 sigma.

A very preliminary analysis of the SuperAGILE data over the same time period and the same sky region does not show any counterpart in the 20-60 keV energy range with an average flux brighter than approximately 30 mCrab.

We strongly encourage multi-frequency observations of the field of the gamma-ray source detected by AGILE.