[vsnet-grb-info 7865] GRB 090519: VLT spectroscopic redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9409
SUBJECT: GRB 090519: VLT spectroscopic redshift
DATE:    09/05/20 08:54:17 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo at brera.inaf.it>

C. C. Thoene (INAF/OAB), P. Jakobsson, A. De Cia (U. Iceland), A.J. 
Levan (Univ. Warwick), J.P.U. Fynbo, J. Hjorth, D. Malesani (DARK/NBI), 
N.R. Tanvir (U. Leicester), D. Fugazza (INAF/OAB), P. D'Avanzo (U. 
Bicocca & INAF/OAB) report on behalf of a larger collaboration:

Using FORS2 on the ESO Very Large Telescope, we have obtained 
low-resolution spectra (3 x 30 min) of the optical afterglow of GRB 
090519 (Perri et al., GCN 9400; Thoene et al., GCN 9403) with the grism 
300V, covering the wavelength range 3500-9200 AA. In the acquisition 
image  the afterglow has a magnitude of R ~ 23.5. The first spectrum 
was  taken approximately 4 hours after the burst.

In a preliminary analysis we detect a break around 4400 AA and strong 
absorption features around 5000 AA and 5900 AA. We interpret these 
features as the Lyman limit, Lyman-beta and Lyman-alpha at a redshift of 
z = 3.85. This is in agreement with the photometric redshift reported by 
Rossi et al. (GCN 9408).

We thank the Paranal staff for excellent support, in particular Gianni 
Marconi, Kieran O'Brien and Patricia Guajardo.