TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3142 SUBJECT: GRB050319, optical observations DATE: 05/03/25 18:14:38 GMT FROM: Adalberto Piccioni at Astronomy, Bologna U. G. Greco, C. Bartolini, A. Guarnieri, A. Piccioni (Bologna University), P. Ferrero (Osservatorio e Universita' di Teramo), G. Pizzichini (IASF-CNR, Sezione di Bologna) and I. Bruni (Osservatorio di Bologna) report: We observed the error box of GRB050319 (SWIFT trigger 11162; Krimm et al., GCN 3117) in Rc light on March 20 in good sky conditions (seeing approx. 1.5 - 2 arcsec) but in presence of high contribution of moonlight with the 152 cm G.D. Cassini telescope of Bologna University, equipped with the BFOSC CCD imager. We got 4X1200s images with the following results: UT at start exposure Exposure (s) OT Rc mag 2005 March 20, 2:14 1200 19.58 (+- 0.18) 2005 March 20, 2:37 1200 19.66 (+- 0.16) 2005 March 20, 3:02 1200 19.67 (+- 0.16) 2005 March 20 3:25 1200 19.69 (+- 0.19) obtained using as comparisons the following objects extracted from the USNO A2 catalog: ID: 1275-07685084 ID: 1275-07684473 ID: 1275-07683651 ID: 1275-07685059 ID: 1275-07684793 ID: 1275-07685268 ID: 1275-07684751 From our images, by comparison with the R magnitudes reported by CGN 3124, 3139 and 3140 we infer a substantial rebrightening. An image of the OT is posted into a public directory from where it can be retrieved by sftp using hostname: ermione.bo.astro.it, username: publicGRB, password: GRB_bo and directory: GRB050319.