[vsnet-grb-info 2193] GRB050922C: TNG spectroscopic observations

[GCN Circulars]

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  <piranomonte at mporzio.astro.it>

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 at 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.

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