TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4032 SUBJECT: GRB050922C: TNG spectroscopic observations DATE: 05/09/23 17:37:41 GMT FROM: Silvia Piranomonte at OAR S. Piranomonte (INAF/OAR), A. Magazzu (TNG), G. Mainella (TNG), F. Fiore (INAF/OAR), S. Covino (INAF/OABr), D. Fugazza (INAF/OABr), A. Antonelli (INAF/OAR), G. Israel (INAF/OAR), G. Chincarini (Univ. Milano-Bicocca), D. Malesani (SISSA), , F. Mannucci (INAF/Arcetri), G. Tagliaferri (INAF/OABr), and L. Stella (INAF/OAR) on behalf of the CIBO collaboration, report: Starting on September 22 21:17:35 UT (about 82 min after the GRB trigger) we have obtained low resolution spectra of the optical afterglow of GRB050922C (Rykoff et al. GCN#4012). The observations consisted of 5 exposures for 300 sec each with DOLORES@TNG, using grism LR-B, with a 1" slit. This set-up provides a resolution of about 5 angstrom. At the time of the observations the afterglow magnitude varied between R~16.7 and R=17.7. A preliminary analysis of the data confirms a very rich spectrum (see Jakobsson et al. GCN#4017, GCN#4029). We detect strong Lyalpha, SiII1304, CII1334, SiIV1393, SiII1526, CIV1548,1550, AlII1670, SiII1808 absorption lines at z=2.198+/-0.001, We also confirm the strong Lyalpha absorption at z=2.07. A full analysis is underway. We thank the TNG staff for the excellent support in performing these observations. This message can be quoted.