TITLE: GCN CIRCULAR NUMBER: 13280 SUBJECT: Fermi/GBM detection of a burst from the magnetar 1E 2259+5 DATE: 12/05/04 17:51:15 GMT FROM: Chryssa Kouveliotou at MSFC S. Foley (UCD), C. Kouveliotou (NASA/MSFC), Y. Kaneko (Sabanci University) and Andrew Collazzi (NASA/ORAU) report on behalf of the Fermi/GBM Team: � At 08:17:43.71 UT on 21 April 2012, the Fermi Gamma-Ray Burst Monitor triggered on a short, soft event very similar to an SGR burst (trigger 356689065/120421346). � The on-ground calculated location is RA = 357.0, DEC = 40.0(J2000 degrees, equivalent to 23h 48 m, 40d 00'), with an uncertainty of 12 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). This location is consistent with 1E 2259+586, albeit with a large error radius. � The event had a duration of ~ 40 ms (20-100 keV) and was equally well fit either with an OTTB function of kT=85+-17 keV or with a single blackbody spectrum of kT=17+-1 keV. These results are preliminary. � Untriggered event searches between April 18-24, 2012 (+- 3 days around the trigger time) did not reveal any additional bursts at the same significance level from the same direction. � Given the recent report by Archibald et al. (ATel 4080, 2012) about the detection of a flux increase of 1E 2259+586 with Swift, we suggest that this magnetar source was indeed the origin of the GBM burst. � Further observations of the source in multiple wavelengths are encouraged.