AGILE monitoring of the enhanced gamma-ray emission from the Crab Nebula region

ATel #3282; M. Tavani (INAF/IASF Roma and Univ. Tor Vergata), A. Bulgarelli (INAF/IASF Bologna), E. Striani (Univ. Tor Vergata), G. Piano, V. Vittorini (INAF/IASF Roma), F. Gianotti, M. Trifoglio (INAF/IASF Bologna), C. Pittori, F. Verrecchia (ASDC), A. Argan, A. Trois, G. De Paris, S. Sabatini, E. Costa, I. Donnarumma, M. Feroci, L. Pacciani, E. Del Monte, F. Lazzarotto, P. Soffitta, Y. Evangelista, I. Lapshov (INAF-IASF-Rm), P. Caraveo, A. Chen, A. Giuliani, S. Mereghetti, F. Perotti (INAF-IASF-Milano), M. Marisaldi, G. Di Cocco, C. Labanti, F. Fuschino, M. Galli (INAF/IASF Bologna), G. Pucella, M. Rapisarda (ENEA-Roma), S. Vercellone, F. D'Ammando (IASF-Pa), A. Pellizzoni, M. Pilia (INAF/OA-Cagliari), G. Barbiellini, F. Longo (INFN Trieste), P. Picozza, A. Morselli (INFN and Univ. Tor Vergata), M. Prest (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P. W. Cattaneo, A. Rappoldi (INFN Pavia), P. Giommi, P. Santolamazza, F. Lucarelli, (ASDC), G. Valentini, L. Salotti (ASI)
on 14 Apr 2011; 16:33 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Marco Tavani (tavani@iasf-roma.inaf.it)

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AGILE is monitoring the gamma-ray emission from the Crab Nebula region, and enhanced flux above 100 MeV is currently detected from a source positionally consistent with the Crab Nebula.

AGILE-GRID detected the following gamma-ray fluxes above 100 MeV (pulsar plus nebula):

MJD=55660.9-55662.9, 2011-04-09 23:45 UT - 2011-04-11 23:45 UT, F = (3.5 +/- 1.3) 10^{-6} ph/cm^2/sec

MJD=55662.9-55664.9, 2011-04-11 23:45 UT - 2011-04-13 23:45 UT, F = (6.5 +/- 1.5) 10^{-6} ph/cm^2/sec.

(We recall that the long timescale average flux from the Crab pulsar + Nebula in the AGILE-GRID energy range above 100 MeV is F = (2.2 +/- 0.15) 10^{-6} ph/cm^2/sec).

No significant flux variation is detected by AGILE during the 2-day interval MJD = 55660.9-55662.9 that includes the detection interval recently reported by Fermi-LAT (ATel # 3276). Significantly enhanced gamma-ray emission from the Crab Nebula above F = 5 10^{-6} ph/cm^2/sec (E > 100 MeV) is detected by AGILE on a 2-day timescale integration starting on April 12, 2011.

Enhanced gamma-ray emission from the Crab Nebula is currently being detected by AGILE, with indications of short-timescale variations. We strongly encourage multifrequency observations of the Crab Nebula.