{
  "bibcode": "2018GCN.23488....1I",
  "body": "L. Izzo, A. de Ugarte Postigo, D. A. Kann (all HETH/IAA-CSIC), D. B. \nMalesani (DAWN/NBI/DTU and DARK/NBI), K. E. Heintz (Univ. of Iceland), \nN. R. Tanvir (Univ. Leicester), V. D'Elia (SSDC), K. Wiersema (Univ. \nWarwick), C. Kouveliotou (GWU), and A. J. Levan (Univ. Warwick) report \non behalf of the Stargate collaboration:\n\nWe observed the optical counterpart (Podesta et al., GCN #23470; Kong, \nGCN #23475; Lipunov et al., GCN #23476; Volnova et al., GCN #23477; \nHeintz et al., GCN #23478; Mazaeva et al., GCN #23479; Watson et al., \nGCN #23481; Belkin et al., GCN #23485; Bolmer & Schady, GCN #23486) of \nthe long, very bright INTEGRAL GRB 181201A (Mereghetti et al., GCN \n#23469) with the ESO VLT UT1 equipped with the FORS2 spectrograph. We \nobtained a single 600 s spectrum in the low-resolution grism 300V. \nObservations started at 00:50:50 UT on December 2 (i.e., 22.16 hr after \ntrigger).\n\nIn the spectrum, the continuum is detected at excellent signal-to-noise \nbut is largely featureless. From a non-detection of any break in the \ncontinuum down to 3500 ��, we derive a redshift upper limit of z < 1.88. \nThere are no strong lines visible, but we note the possible presence of \nthree weak lines, which, if real, can be identified as the Mg II doublet \nand Mg I, implying a redshift of z = 0.450. No emission lines are \nvisible. Pan-STARRS archive imaging (Chambers et al. 2016, \narXiv:1612.05560) shows the presence of a possible host galaxy at i' ~ \n23.4 mag.\n\nWe acknowledge the ESO observing staff at Paranal, especially Cedric \nLedoux, Joe Anderson, and Rodrigo Tomero. We are also indebted to the \nESPRESSO commissioning team who kindly granted us permission to carry \nout this ToO observation during their time.",
  "circularId": 23488,
  "createdOn": 1543769628000,
  "email": "kann@iaa.es",
  "subject": "GRB 181201A: VLT/FORS2 tentative spectroscopic redshift",
  "submitter": "Alexander Kann at IAA-CSIC  <kann@iaa.es>",
  "eventId": "GRB 181201A"
}