GCN Circular 15187
Subject
GRB 130907A: NOT redshift
Date
2013-09-07T23:44:37Z (12 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Xu (DARK/NBI), D. Malesani (DARK/NBI),
J. Gorosabel (IAA-CSIC/UPV-EHU), P. Jakobsson (U. Iceland) and J. Kajava (NOT) report
on behalf of a larger collaboration:
We observed the optical afterglow of GRB 130907A (Page et al., GCN 15183; Gorbovskoy
et al., GCN 15184) with the NOT equipped with the AlFOSC spectrograph and camera.
The transient is clearly detected in our acquisition images, taken in a clear filter, at the
following coordinates:
RA(J2000) = 14:23:34.08
Dec(J2000) = +45:36:26.7
Using R-band values from nearby USNO stars, we get a magnitude R = 16.7 +- 0.1 at a
mean time of 0.41 hr after the GRB, where the error is dominated by calibration
uncertainties.
A single spectrum of 900 s covering the range from 3800 to 8000 AA, with a resolution of
~700, was obtained with a mean epoch of 0.598 hr after the burst. The spectrum presents
a strong continuum with deep spectral features of AlIII, FeII, MgII and MgI at a common
redshift of z=1.238 (wavelength calibration based on archival data), which we identify as
the redshift of the GRB.