GCN Circular 28717
Subject
GRB 201020A: Redshift from GTC/OSIRIS
Event
Date
2020-10-21T10:30:41Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), M. Blazek, J. F. Agui Fernandez, C. C. Thoene (all
HETH/IAA-CSIC), G. Lombardi (GRANTECAN, IAC) and A. Tejero (GRANTECAN)
report:
We observed the afterglow (Ambrosi et al., GCN#28696; Adachi et al.,
GCN#28697; Fu et al., GCN#28701; Belkin et al., GCN#28703; Pankov et
al., GCN#28708; Kumar et al., GCN#28711; Paek et al., GCN#28713) of GRB
201020A (Ambrosi et al., GCN#28696; Sakamoto et al., GCN#28705; Bissaldi
et al., GCN#28706) with the 10.4m GTC telescope, at Roque de los
Muchachos Observatory (La Palma, Spain) equipped with OSIRIS. The
observation started on 20 October 2020 at 20:08 UT (14.34 hrs after the
GRB onset) and consisted of 4 x 900s with the R1000B grism, covering the
wavelength range between 3700 and 7800 AA. Observations were taken under
inclement conditions, with bad seeing and thick clouds passing through.
The spectrum shows a clear continuum, consistent with the Lyman forest,
Ly-alpha, SiII, OI, CII, SiIV, CIV, FeII, FeII*, and AlII, all at a
common redshift of z = 2.903, which we identify as the redshift of the
GRB.