TITLE: GCN GRB OBSERVATION REPORT NUMBER: 921 SUBJECT: IPN/RXTE TRIANGULATION OF GRB010126 DATE: 01/01/26 21:07:32 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, and D. Smith, on behalf of the RXTE ASM GRB team, report: This burst, which was incorrectly reported as occurring on the 25th in today's GCN notice, was observed, with rather poor statistics, by Ulysses. It had a duration of ~10 s, a 25-100 keV fluence of ~2 x 10^-6 erg/cm^2, and a peak flux over 0.25 s of ~7 x 10^-7 erg/cm^2 s. These numbers should be regarded as very approximate due to the weakness of the burst. We have done a very rough, preliminary triangulation using the RXTE ASM 5 - 12 keV data and the Ulysses 25 - 150 keV data. Although the time histories are somewhat different in these two energy ranges, the result indicates that the GRB came from the northern part of the RXTE ASM error box, above declination ~ 49 o 20 '. If this event was observed by Konus-WIND or NEAR, a smaller error box can probably be derived. [GCN OPS NOTE: Please note that the calendar dates for the recent GCN/RXTE_ASM_GRB_POSITION Notice contained an error. The date was listed as GRB_DATE: 11935 TJD; 25 DOY; 01/01/25 but the correct dates are GRB_DATE: 11935 TJD; 26 DOY; 01/01/26 This error occurred in the GCN processing of the ASM message -- it was not part of the original ASM submission. The burst occurred today, and not yesterday as might be inferred by casual inspection of the DOY or YY/MM/DD fields. GCN apologizes for this error.]