TITLE: GCN CIRCULAR NUMBER: 7757 SUBJECT: GRB 080520: VLT redshift DATE: 08/05/21 11:38:56 GMT FROM: Pall Jakobsson at U Hertfordshire Pall Jakobsson (U. Hertfordshire), Johan P. U. Fynbo, Daniele Malesani, Jens Hjorth and Bo Milvang-Jensen (DARK, NBI) report on behalf of a larger collaboration: Using FORS2 on the Very Large Telescope, we have obtained 3*30 min spectra (grism 300V) of the optical afterglow of GRB 080520 (Grupe et al., GCN 7753). The acquisition image shows it to have R = 23.0 +/- 0.5 on May 21.235 (7.3 hours post burst). A firm upper limit of z < 2.4 can be placed on the redshift of GRB 080520 from the lack of Ly-alpha forest lines in the spectrum of the afterglow. This is consistent with the GROND observations (Rossi et al., GCN 7756). The combined spectrum shows an emission line, presumably corresponding to [O II] 3727 at z = 1.545. At this redshift we also find the Mg II doublet (2796,2803) and Mg I (2852). We thank the Paranal staff for excellent support, especially Yuri Beletsky and Patricia Guajardo.