GCN Circular 30355
Subject
GRB 210702A: Swift/UVOT redshift
Date
2021-07-02T23:27:24Z (3 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) reports on behalf of the Swift/UVOT team:
The Swift/UVOT obtained a 49s grism spectrum of GRB 210702A
starting 282 s after the BAT trigger (Lien et al., GCN Circ. 30351).
The spectrum shows a clear break at 2011 Angstrom, and absorption features
attributable to Ly-alpha and Ly-beta suggesting
a redshift of z=1.1757+/-0.0093. An possible intervening system is present
at
z=1.050 based on a weaker line seen at 2492A.
The wavelength anchor/zeropoint in the uv grism is uncertain by typically
15A, which translates to an uncertainty as quoted in the redshift above.