[vsnet-grb-info 4421] GRB 070306: possible emission-line redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6202
SUBJECT: GRB 070306: possible emission-line redshift
DATE:    07/03/12 20:37:34 GMT
FROM:    Andreas O. Jaunsen at ITA/U Oslo  <ajaunsen at astro.uio.no>

A.O. Jaunsen (Univ. Oslo), C.C. Thoene, J.P.U. Fynbo, J. Hjorth (DARK/ 
NBI),
P. Vreeswijk (ESO) report on behalf of a larger collaboration.

We observed the field of GRB 070306 (Pandey et al., GCN 6169 & GCN  
Report 38.1)
with the ESO/VLT equipped with FORS2. Observations started on 2007  
Mar 08.11 UT
(about 34 hr after the GRB) and three 1800-s spectra were acquired  
with the
300V grism covering a wavelength range of 3500-9500A.

The spectrum consists of a largely featureless continuum from about  
4000-9400A
with the exception of an apparent emission line at ~9310A. The  
emission-line
is very close to the prominent telluric skyline at 9313A, but is seen  
in each
of the three individual spectra. The lack of other detected lines in the
observed wavelength range suggests that the emission line is due to  
[O II] at
a red-shift of z=1.497. It should be cautioned, however, that this  
host galaxy
appears to be highly reddened (as already noted by Rol et al., GCN  
6174), which
could have an unforeseen suppression-effect on the bluer part of the  
spectrum.

We acknowledge the excellent support from the ESO/Paranal staff.