GCN Circular 13280

S. Foley (UCD), C. Kouveliotou (NASA/MSFC), Y. Kaneko (Sabanci 
University) and Andrew Collazzi (NASA/ORAU) report on behalf 
of the Fermi/GBM Team:
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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).
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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.
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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. 
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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. 
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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.
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Further observations of the source in multiple wavelengths are 
encouraged.