TITLE: GCN CIRCULAR NUMBER: 19598 SUBJECT: Fermi/GBM observation of a bright burst from magnetar SGR 1935+2154 DATE: 16/06/27 01:41:53 GMT FROM: George A. Younes at George Washington U George Younes (GWU), Chryssa Kouveliotou (GWU), Rachel Hamburg (UAH), and Eric Burns (UAH) report on behalf of a larger collaboration: "At 13:54:30.75 UT on 26 June 2016, the Fermi Gamma-Ray Burst Monitor triggered on a bright, SGR-like burst from the direction of the magnetar SGR 1935+2154 (trigger 488642074/160626580). This burst also triggered Swift/BAT (GCN #19590, Barthelmy et al. 2016). The burst has a duration of T90 ~ 700 +/- 20 ms in the energy range 10-200 keV. It is well-fit by a two blackbody model with temperatures of kT1 = 8.0 +/- 0.1 keV and kT2 = 14.0 +/- 0.3 keV. The corresponding flux in the energy range 10-200 keV is (2.49 +/- 0.01)E-05 erg/s/cm^2. The peak flux integrated over 16 ms is (3.6 +/- 0.1)E-05 erg/s/cm^2. We note that the source has been undergoing an outburst since 2016 May 14, with a total of 39 GBM triggers. This is the third activation of the source following its July 2014 and February 2015 outbursts. The analysis results presented above are preliminary, and the full analysis of the bursts from all three outbursts is underway." -- George A. Younes, PhD Postdoctoral Researcher The George Washington University Physics department 725 21st St NW, Washington, DC 20052