Further to the item on IAUC 7094, M. Feroci and L. Piro, Istituto di Astrofisica Spaziale, CNR, Rome; F. Frontera, Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Bologna, and University of Ferrara; V. Torroni and M. Smith, BeppoSAX Science Operation Center, Telespazio, Rome; and J. Heise and J. in 't Zand, Space Research Organization of the Netherlands, Utrecht, provide the following elaboration of the information given on GCN 199 and 202: "A gamma-ray burst triggered the BeppoSAX Gamma-Ray Burst Monitor (GRBM) on Jan. 23.40780 UT. The burst was also detected in the Wide Field Camera (WFC) 1. The GRBM lightcurve shows a multipeak complex structure that lasts for about 100 s with two major peaks. The intensity of the highest peak is 11 200 counts/s in the band 40-700 keV. A preliminary estimation of the fluence is (3.5 +/- 0.4) x 10E-4 erg cmE-2 sE-1. This is the brightest burst detected so far by the BeppoSAX GRBM simultaneously with the WFC. The WFC lightcurve, which lasts for a comparable time, is also complex, with one peak followed by a structured, higher plateau. The WFC peak intensity corresponds to a flux of 3.4 Crab in the energy band 1.5-26 keV, and it is reached about 40 s afterthe GRBM peak. The position of the x-ray counterpart to GRB 990123, as derived by the quicklook WFC image, is R.A. = 15h25m29s, Decl. = +44o45'.5 (equinox 2000.0), with an error radius of 2' (99-percent confidence level). A follow-up observation with BeppoSAX narrow- field instruments is in progress."
International Astronomical Union Circular
- Pub Date:
- January 1999