TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2354 SUBJECT: IPN detection of continued activity from SGR1806-20 DATE: 03/08/18 23:28:52 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses and Mars Odyssey GRB teams, I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and A. Sanin, on behalf of the HEND-Odyssey GRB team, and W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS-Odyssey GRB team, report: Ulysses and Mars Odyssey (HEND) observed this unusually long SGR burst. As observed by Ulysses, it had a duration of approximately 1 second, a 25-100 keV fluence of approximately 7.3E-06 erg/cm2, and a peak flux of approximately 1.9E-05 erg/cm2 s over 0.25 seconds. We have triangulated it to a preliminary annulus centered at RA, Decl(2000)=340.644, -22.919 degrees, whose radius is 63.096 +/-0.013 degrees (3 sigma). As the center line of this annulus passes 0.003 degrees from the position of SGR1806-20, we consider it most likely that this event originated from that SGR. If so, the Earth-crossing time was 50231 seconds. However, due to the present configuration of the IPN, Ulysses/Mars, Mars/Earth, and Ulysses/Earth annuli which are consistent with the position of SGR1806-20 will also be consistent with portions of the error circle for the possible new SGR, 1808-20 (GCN 2351). Depending on the exact position of SGR1808-20, however, the converse is not necessarily true. Thus it may be possible to confirm the existence of this new source with the IPN if it bursts again. The situation is illustrated with a map which has been posted at ssl.berkeley.edu/ipn3/030818.