GCN Circular 9250
Subject
GRB 090424: WHT ISIS spectroscopy
Date
2009-04-25T17:23:03Z (15 years ago)
From
Klaas Wiersema at U of Leicester <kw113@star.le.ac.uk>
K. Wiersema (Leicester), A. de Ugarte Postigo (ESO) and A. Levan (Warwick)
report on behalf of a larger collaboration:
We observed the afterglow of GRB 090424 (Cannizzo et al, GCN 9223) with
the ISIS spectrograph on the William Herschel Telescope at the
Observatorio del Roque de los Muchachos on La Palma, ~8 hours after burst.
In the spectrum we find several lines, among others the Mg II doublet
(with restframe EW > 1 A of the 2796 line), Fe II, Na I. Through these we
confirm the redshift of z=0.544 found by Chornock et al (GCN 9243).
Continuum is detected up to at least 3200 A, giving an upper limit to the
GRB redshift of 1.6, consistent with the emission and absorption redshift
of 0.544.
We thank the staff of the WHT, in particular O. Vadivescu, for support for
these observations.