TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1045 SUBJECT: Possible precursor to the SGR1900+14 giant burst DATE: 01/04/20 19:48:21 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, and E. Montanari, C. Guidorzi, F. Frontera, and M. Feroci, on behalf of the BeppoSAX GRBM team, report: We have identified a likely precursor to the giant flare from SGR1900+14 (GCN 1041, 1043) in the Ulysses data. This event occurred on April 17, 2001, ~42184 s at Ulysses, and if it was indeed from SGR1900+14, its Earth-crossing time would have been ~42332 s. This burst was ~50 s long, and its time history resembles that of the April 18 event, although it is considerably less intense. Its 25-100 keV fluence was ~2.3x10^-5 erg/cm^2, and its peak flux over 0.5 s was ~1.5x10^-6 erg/cm^2 s. Due to a high solar proton background, these numbers are subject to more than the usual uncertainties. As SGR1900+14 was Earth-blocked at BeppoSAX, it did not observe this event, and there is no localization data available. The time history has been posted at ssl.berkeley.edu/ipn3/010417. Also, we note that the time history of the April 18 event, posted at ssl.berkeley.edu/ipn3/010418, was incorrectly labelled "Counts/ 0.5 s". The label should have read "Counts/Second". A corrected plot has been posted. Searches are underway through the Ulysses data for more possible events from this source.