{
  "bibcode": "2021GCN.29806....1D",
  "body": "A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), B. Sbarufatti (PSU), \nD. Xu (NAO/CAS), J.-B. Vielfaure (APC, Paris University), D. B. Malesani \n(DTU Space), D. A. Kann (HETH/IAA-CSIC) V. D'Elia (ASI/SSDC, INAF/OAR), \nP. J. Pessi (FCAG/ESO), report on behalf of the Stargate consortium:\n\nWe observed the optical afterglow of GRB 210411C (Sbarrato et al., GCN \n29794) using the ESO VLT UT3 (Melipal) equipped with the X-shooter \nspectrograph. Our spectra cover the wavelength range 3000-21000 AA, and \nconsist of 4 exposures by 1200 s each (8x600 s in the NIR). The \nobservation mid time was 2021 Apr 12.33 UT (16.9 hr after the GRB).\n\nIn a 60 s image taken with the acquisition camera on Apr 12.294 UT, we \ndetect the optical afterglow, for which we measure an AB magnitude r = \n21.69 +- 0.04 (calibrated against nearby stars from the SkyMapper \ncatalog; Wolf et al. 2018, PASA, 35, 010; \nhttps:doi.org/10.4225/41/593620ad5b574).\n\nWe clearly detect continuum over the wavelength range 3520 - 17500 AA. A \ntrough is visible around 4650 AA, which we identify as due to H I. From \nthe detection of several narrow absorption features, which we interpret \nas due to, among others, Si II, Si II*, O I, C II, Si IV, C IV, Fe II, \nAl II, we infer a redshift z = 2.826. We also identify the FeII* 2396 \nfine-structure transition, though at low S/N.\n\nWe acknowledge excellent support from the observing staff at Paranal, in \nparticular Eleonora Sani and Bin Yang.\n\n[GCN OPS NOTE(12apr2021):  Per author's request, GRB in the SUBJECT line\nwas changed from 210411A\" to the correct name \"210411C\".]",
  "circularId": 29806,
  "createdOn": 1618224415000,
  "email": "malesani@space.dtu.dk",
  "subject": "GRB 210411C: VLT/X-shooter redshift",
  "submitter": "Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>",
  "eventId": "GRB 210411C"
}