Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 14478

GRB 130427A: NOT optical photometry and redshift
2013-04-28T00:47:29Z (11 years ago)
Dong Xu at DARK/NBI <>
D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), S.
Schulze (PUC and MCSS), J. Jessen-Hansen (AU), G. Leloudas (OKC,
Stockholm), T. Kruehler, J.P.U. Fynbo (DARK/NBI), P. Jakobsson (U.
Iceland) report on behalf of a larger collaboration:

We observed the field of GRB 130427A (Maselli et al., GCN 14448) with
the 2.5m Nordic Optical Telescope (NOT) equipped with the ALFOSC
camera. Observations started at 20:39:12 UT on 2013-04-27 (i.e., 12.85
hr after the BAT trigger).

We first obtained a series of frames in the sloan u-, g-, r-, i-, and
z-band filters. The optical afterglow (ref., Elenin et al., GCN 14450)
is clearly detected in the stacked images in each of these filters.
Preliminary analysis gives the following magnitudes


at a mean time of 12.96 hr post-trigger, calibrated with nearby stars
in the SDSS field.

We also carried out a 1800s spectroscopic exposure. The spectrum
covers 3200 - 9100 AA at a resolution of ~700 and has a high S/N. We
detect prominent absorption lines of the MgII doublet, MgI and CaII K
& H as well as weak emission lines of the [OII] doublet and H-beta,
all at a common redshift of z=0.338+/-0.002, consistent with the
redshift reported by Levan et al. (GCN 14455).
Looking for U.S. government information and services? Visit