Skip to main content
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

GCN Circular 30583

GRB 210731A: VLT/X-shooter redshift
2021-08-02T09:53:24Z (3 years ago)
Andrew Levan at U.of Leicester <>
D.A. Kann (HETH/IAA-CSIC), L. Izzo (DARK/NBI), A.J. Levan (Radboud),  D.B. Malesani (DTU Space), S. de Wet (UCT) report for the STARGATE collaboration: 

"We observed the afterglow of GRB 210731A (Troja et al. GCN 30568, de Wet et al. GCN 30570) with the ESO VLT UT3 equipped with the X-shooter spectrograph on 1 Aug 2021. A total of 4800 s (4x1200 s) of spectra were obtained starting at 02:45 UT (approximately 28.5 hours after the burst). 

The afterglow is well detected in the acquisition imaging with r=20.7+/- 0.1, and a continuum is visible across the X-shooter spectral range. The spectra contain several prominent absorption features of Fe II, Al III, Mg II and Mg I, at a common redshift z=1.2525. This is consistent with the detection of the afterglow in all the UVOT filters (Kuin & Troja GCN 30572), and we suggest it to be the redshift of GRB 210731A. 

We thank the Paranal staff for the excellent assistance in securing these observations."
Looking for U.S. government information and services? Visit