TITLE: GCN CIRCULAR NUMBER: 6458 SUBJECT: GRB 070518: optical observation DATE: 07/05/23 15:53:05 GMT FROM: Giuseppe Greco at U Bologna F. Terra (Second University of Roma "Tor Vergata"), G. Greco, C. Bartolini, A. Guarnieri, A. Piccioni (Bologna University), G. Pizzichini (INAF/IASF Bologna), D. Nanni (INAF/OAR and Second University of Rome "Tor Vergata"), S. Karpov (Special Astrophysical Observatory, Russia), S. Galetti and R. Gualandi (Bologna Observatory) report: During the night of 07/05/18 we observed the OT of GRB070518 (Guidorzi et al., GCN 6415) with the 1.52 cm telescope of the Bologna Observatory in Loiano under moderate sky conditions (seeing ~ 2"). The OT flux was slightly blended with a nearby star (R ~ 18.7). To correct for the blending we employed difference image analysis techniques. By adding two consecutive 30 min exposures in the Rc filter at mean time 23.5 UT we find Rc = 22.3 +/- 0.2 based on the USNO-A2.0 catalog. Our coadded image have been posted in our public directory from where they can be retrieved by sftp using hostname: ermione.bo.astro.it username: publicGRB password: GRB_bo.