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TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1953 SUBJECT: VLT/FORS2 spectra of GRB 030323 DATE: 03/03/25 06:02:12 GMT FROM: Paul Vreeswijk at ESO <pvreeswi@eso.org> Paul Vreeswijk (ESO), Ralph Wijers, Evert Rol (U. of Amsterdam), and Jens Hjorth (U. of Copenhagen) report for the GRACE collaboration: The field of GRB 030323 (HETE trigger 2640) was observed last night (March 24/25) in spectroscopic mode with FORS2 at unit-4 of ESO's VLT at Paranal, Chile. The total exposure time was 1 hour in the 300V and 300I grisms, covering approximately 4000-9300 A with a resolution of about 12 A. The slit (1" wide) was positioned to cover the position of the presumed afterglow (Gilmore, Kilmartin & Henden, GCN 1949; see also GCN 1952), as well as a nearby reference object. Preliminary reduction of the 300V spectra of the candidate afterglow shows very strong absorption over the range 516-545 nm, presumably a complex of Ly alpha clouds around z = 3.3-3.4. The detection of numerous narrow lines is consistent with this interpretation: we can identify these with metal-absorption lines (SiII, OI, CII, SiIV, CIV, AlII) at a redshift of z = 3.372. These Ly alpha and metal-absorption lines probably originate in the host galaxy of GRB 030323. We appreciate the assistance of the ESO staff at Paranal; in particular of Thomas Szeifert and Olivier Marco.
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