{
  "bibcode": "2021GCN.30487....1T",
  "body": "C. C. Thoene (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,\nDARK/NBI),  D. A. Kann, M. Blazek, J. F. Agui Fernandez (all\nHETH/IAA-CSIC), J. P. U Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), N. R. Tanvir\n(U. Leicester) and N. Castro (GTC) report:\n\nWe obtained spectroscopy of the afterglow of GRB 210722A (D���Avanzo et al.\nGCN #30475, Page et al. GCN #30483, Zhu et al. GCN #30476) with OSIRIS\nmounted on the 10.4 m GTC telescope at the Roque de los Muchachos\nobservatory (La Palma, Spain). Observations started at 05:02:09 UT with a\nmid-time of 05:17:30 UT (8.38 hr after the burst) and consisted of 2x900s\nspectra taken with grism R1000B, which covers the spectral range between\n3700 and 7800 AA. We also obtained an acquisition image of 60s in r'-band\nat 04:58:25 UT. Observing conditions were rather bad with a seeing of 1.7\narcsec and taken during morning twilight.\n\nWe detect several weak absorption lines, consistent with the MgII doublet,\nFeII 2344, 2374, 2383, 2587 and 2600 at a common redshift of z=1.145. The\nlines are in the weakest 1.7% of the average GRB absorption line strength\n(de Ugarte Postigo et al. 2012, A&A 548, 11). The detection of the\nafterglow in all UVOT filters (Siegel et al. GCN #30482) is consistent with\nthis redshift.\n\nThe acquisition image shows the afterglow to be r��� = 18.92 +/- 0.03\ncompared to 7 SDSS field stars.",
  "circularId": 30487,
  "createdOn": 1627062629000,
  "email": "christina.thoene@gmail.com",
  "subject": "GRB 210722A: Redshift from OSIRIS/GTC",
  "submitter": "C. C. Thoene at HETH/IAA-CSIC  <christina.thoene@gmail.com>",
  "eventId": "GRB 210722A"
}