TITLE: GCN CIRCULAR NUMBER: 2763 SUBJECT: Very strong outburst from SGR 1806-20 detected with INTEGRAL DATE: 04/10/05 14:49:51 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti, D. Gotz (IASF-Milano), J.Borkowski (CAMK-Torun), M.Beck (ISDC-Versoix) on behalf of the IBAS Localization Team and F.I.Mirabel (SAp-Saclay) on behalf of the INTEGRAL Science Working Team report: A strong increase in the activity of SGR 1806-20 has been detcted by IBAS starting at 13:57 UT of October 5. The activity consists of an approximately 6 min long, multipeaked outburst, followed by a few shorter bursts. During the peaks of the long outburst the counting rate in the IBIS/ISGRI detector saturates the available telemetry. Analysis is in progress to estimate the event fluence and spectrum. Rapid observations at other wavelengths are encouraged. This message can be cited.