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SGR 0501+4516: AGILE observations

ATel #1705; M. Feroci, L. Pacciani, E. Del Monte, Y. Evangelista, I. Donnarumma, F. Lazzarotto, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IASF Rome), A. Giuliani, S. Vercellone, A. Chen, S. Mereghetti, A. Pellizzoni, F. Perotti, F. Fornari, P. Caraveo (INAF/IASF Milan), 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, A. Argan, A. Trois (INAF/IASF Rome), 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), and C. Pittori, F. Verrecchia, B. Preger, P. Santolamazza, S. Colafrancesco, P. Giommi (ASDC) and L. Salotti (ASI)
on 8 Sep 2008; 15:07 UT
Credential Certification: Marco Feroci (marco.feroci@iasf-roma.inaf.it)

Subjects: X-ray, Gamma Ray, Soft Gamma-ray Repeater

The AGILE mission started a Target of Opportunity observation on the new soft gamma repeater SGR 0501+4516 (Barthelmy et al., GCN 8113) on 2008 August 31st, 12 UT. After the first week of observation, only 2 short bursts were detected with SuperAGILE from this source. Under the assumption of a Crab-like spectrum, the burst properties in the 17-60 keV energy range are:

        Date         Duration     10-ms Peak Flux   Fluence 
(UT) (ms) (erg/cm2/s) (erg/cm2)

2008-09-03 10:06:38 50 2.3e-6 6.4e-8
2008-09-03 18:53:51 70 1.9e-6 7.6e-8
Other events may have occurred in the periods when the source was occulted to the AGILE view by the Earth (approximately 35% of the time, on the average). Another event had been detected by SuperAGILE through the collimator shields on 2008-08-26 03:16:15 UT (100 ms, very bright, also detected by Konus-Wind, Konus-Wind team, private communication), when AGILE was pointing 140 degrees away from the SGR.
The two bursts of 2008-09-03 were not detected by the MCAL and GRID instruments. The MCAL 3-sigma upper limit is 4e-8 erg/cm2 in the 0.5-1 MeV energy range, over the burst duration as observed by SuperAGILE.
No persistent emission was observed at the position of SGR 0501+4516 by either SuperAGILE or GRID. The 3-sigma upper limit in the 20-60 keV energy range is about 8 mCrab, consistent with the 2 mCrab detection by INTEGRAL (Hurley & Gotz, GCN 8163). The 2-sigma upper limit in the >100 MeV energy range is 13e-8 ph/cm2/s.
The AGILE observation will continue until 2008 September 10th.