===== BEGIN MESSAGE ===== From aavso-hen-bounces@aavso.org Mon Apr 27 12:16:01 2009 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on mira.aavso.org X-Spam-Level: X-Spam-Status: No, score=-1.4 required=2.5 tests=ALL_TRUSTED autolearn=disabled version=3.2.5 Received: from mira.aavso.org (localhost.localdomain [127.0.0.1]) by mira.aavso.org (8.14.3/8.14.3) with ESMTP id n3RGFwXC020248; Mon, 27 Apr 2009 12:15:59 -0400 Received: from mira.aavso.org (localhost.localdomain [127.0.0.1]) by mira.aavso.org (8.14.3/8.14.3) with ESMTP id n3RGAlxW020007 for ; Mon, 27 Apr 2009 12:10:47 -0400 Received: (from grb@localhost) by mira.aavso.org (8.14.3/8.14.3/Submit) id n3RGAlbQ020004; Mon, 27 Apr 2009 12:10:47 -0400 Date: Mon, 27 Apr 2009 12:10:47 -0400 Message-Id: <200904271610.n3RGAlbQ020004@mira.aavso.org> To: aavso-hen@aavso.org From: grb@aavso.org Subject: [AAVSO-HEN] GRB 090425: Fermi GBM detection X-BeenThere: aavso-hen@aavso.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: AAVSO High Energy Network List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: aavso-hen-bounces@aavso.org Errors-To: aavso-hen-bounces@aavso.org The following is a GCN Circular circulated via the AAVSO network. For an archive and more information on circulars visit: http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html TITLE: GCN CIRCULAR NUMBER: 9271 SUBJECT: GRB 090425: Fermi GBM detection DATE: 09/04/27 16:10:11 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 09:03:30.57 UT on 25 April 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090425 (trigger 262343012 / 090425377). The on-ground calculated location, using the GBM trigger data, is RA = 116.1, DEC = 69.9 (J2000 degrees, equivalent to 07h 44m, 69d 54'), with an uncertainty of 2.9 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 105 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of three widely separated pulses and has a duration (T90) of about 72 s (8-1000 keV). The first two pulses at T0-0.6 s and T0+44 s are weak and well fit by a simple power law functions with index -1.5 +/- 0.1 and index -1.7 +/- 0.1 respectively. The third pulse observed at T0+57 s is strong and structured. The time-averaged spectrum from T0+57.537 s to T0+80.065 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -1.56 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 142 +/- 13 keV (chi squared 570 for 484 d.o.f.). A Band function fits the spectrum equally well (chi squared 566 for 483 d.o.f.) with Epeak= 69 +/- 11 keV, alpha = -1.29 +/- 0.11 and beta = -2.03 +/- 0.05. The event fluence (8-1000 keV) in this time interval is (1.3 +/- 0.2)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+57.537 s in the 8-1000 keV band is 14.0 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." _______________________________________________ Aavso-hen mailing list Aavso-hen@aavso.org To change options or unsubscribe, goto http://www.aavso.org/mailman/listinfo/aavso-hen The Santa Barbara Instrument Group (www.sbig.com): Proud Sponsor of the American Assocation of Variable Star Observers. ===== END MESSAGE =====