TITLE:   GCN CIRCULAR
NUMBER:  28650
SUBJECT: GRB 201014A: Redshift from GTC/OSIRIS
DATE:    20/10/16 11:04:06 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D.A. Kann, M. Blazek, J.F. Agui Fernandez, C. Thoene (all HETH/IAA-CSIC), G. Gomez Velarde and A. Perez Romero (both GRANTECAN) report:

We observed the afterglow of GRB 201014A (Ambrosi et al. GCN 28623; D���Elia et al. GCN 28626; Pozanenko et al. GCN 28628) with the 10.4m GTC telescope, at Roque de los Muchachos Observatory (La Palma, Spain) equipped with OSIRIS. The observation started on 16 October 2020 at 5:10 UT (30.36 hrs after the GRB onset) and consisted of 3x1200s with the R1000B grism, covering the range between 3700 and 7800 ��. 

The spectrum shows signal redwards of 5150 AA, consistent with the Lyman forest, Lyman alpha, SiII, SiIV, OI, and CII at a common redshift of 4.56, which we identify as the redshift of the GRB.