TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1727 SUBJECT: IPN triangulation of GRB021206 (exceptionally bright; annulus only) DATE: 02/12/07 21:02:39 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses and Mars Odyssey GRB teams, I. Mitrofanov, D. Anfimov, 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 HEND observed this burst at 81155 +/- 1104 s. The uncertainty is due to the fact that no near-Earth spacecraft has yet reported this event. As observed by Ulysses, it had a duration of approximately 20 seconds with a weak tail lasting perhaps another 40 seconds, a 25-100 keV fluence of approximately 1.6E-04 erg/cm2, and a peak flux of approximately 2.9E-05 erg/cm2 s over 0.50 seconds. We have triangulated it to a preliminary annulus centered at RA, Decl (2000)= 328.915, -57.580 degrees, with radius 81.125 +/- 0.014 degrees. (The uncertainty in the radius does not take into account the fact that HEND was driven into saturation by this burst; we will attempt to include this in later estimates). As this annulus does not pass near any of the known SGRs, we believe the event to be a GRB. We are expecting confirmation of this event by a near-Earth spacecraft, which will allow us to derive an error box for it.