TITLE: GCN GRB OBSERVATION REPORT NUMBER: 359 SUBJECT: BeppoSAX NFI Observation of GRB990627 X-ray afterglow DATE: 99/07/01 18:16:26 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma L.A. Antonelli, Osservatorio Astronomico di Roma, L. Nicastro, IFCAI, CNR, Palermo, M.R. Daniele, R. Ricci, BeppoSAX SDC, Telespazio, Roma M. Stornelli, BeppoSAX OCC, Dataspazio, Roma, A. Paolino, BeppoSAX SOC, Telespazio, Roma, E. Pian, E. Palazzi, ITESRE, CNR, G. Gandolfi and L. Piro IAS, CNR on behalf of the BeppoSAX Team report: "The BeppoSAX NFIs observed the region of GRB990627 (GCN 356) from Jun 27.544 (8 hours after the BeppoSAX GRBM+WFC trigger) to Jun 28.864 UT for a total MECS on source exposure time of 29 ksec. A weak X-ray source (1SAX J0148.5-7704) lies within the 3' BeppoSAX WFC error-circle (GCN 356). Source position is RA= 01 48 25.4 DEC= -77 04 38, J2000, error radius 1' and is consistent with the radio source AT J014832.6-770412 reported by Subrahmanyan et al.(GCN 357). This source shows a fading behaviour strongly suggesting we detected the X-ray afterglow of GRB990627. This message may be cited."