[vsnet-grb-info 375] GRB020813: High-resolution optical spectroscopy

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1524
SUBJECT: GRB020813: High-resolution optical spectroscopy
DATE:    02/08/26 10:23:03 GMT
FROM:    Angelo Antonelli at Obs. Astro. di Roma  <angelo@coma.mporzio.astro.it>

F. Fiore, S. Savaglio (also JHU), L.A. Antonelli, A. Fontana, G. Marconi,
L. Stella, A. Di Paola, G. Stratta, G. Israel (INAF-OAR), S. Covino,
G. Chincarini, G. Ghisellini, P. Saracco, F. Zerbi (INAF-OABrera),
D. Lazzati (Cambridge, UK), R. Perna (CfA), M. Vietri (Univ. Roma Tre),
F. Frontera (Univ. di Ferrara), S. Mereghetti (CNR-IASF), 
E.J.A. Meurs (Dunsink Obs.) and N. Kawai (Titech, RIKEN) report:

"Starting on August 13 2002 23:32 UT we have obtained high resolution 
(R=40,000, 7.5 km/s in the observer frame) spectra of the optical 
afterglow of GRB020813 (Fox et al., GCN #1470) using UVES at VLT/Kueyen.
This resolution is 4 times better than the best resolution obtained so 
far for GRB OT spectra, confirming that this kind of observations is 
capable to map accurately the kinematics and metallicities of 
medium-high redshift galaxies. Observations consisted of 3 exposures, 
for a total of 7,700 seconds, covering the full spectral range 3500-9800 
Angstrom, in good seeing conditions (better than 1"). At the time of 
the observations the afterglow magnitude was R=20.4 and V=20.8 (see
Gladders & Hall, GCN #1513). 

A preliminary reduction of the spectra is already revealing the very
rich and complex structure of the ISM in the putative GRB host galaxy.
Strong absorption lines of MgI2852, MgII2803, MgII2796, FeII2344,
FeII2374, FeII2382 at a mean redshift of z = 1.2545 are clearly detected 
(see Price et al., GCN #1475), spanning a total velocity range of up
to about 400 km/s. Several narrow components are resolved down to a
width of a few tens of km/s."

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