{
  "bibcode": "2016GCN.19971....1K",
  "body": "T. Kruehler (MPE Garching), D. Xu (NAOC/CAS), J. Bolmer (MPE Garching \nand ESO Santiago), K. Wiersema (Univ. Leicester), D. Malesani (DARK/NBI \nand DTU Space), R. Sanchez-Ramirez (IAA-CSIC), J. P. U. Fynbo \n(DARK/NBI), report on behalf of a larger collaboration:\n\nWe observed the field of GRB 1601001A (Page et al., GCN 19967) with the \nESO Very Large Telescope Unit 2 (Kueyen) equipped with the X-shooter \nspectrograph.\n\nClose to, but outside, the enhanced XRT position (Osborne et al., GCN \n19969), in our acquisition image we detect a bright, pointlike source at \ncoordinates RA = 04:47:40.71, Dec = -57:15:36.8. This source is faintly \nvisible in the archival DSS data and is pointlike in our images (0.75\" \nseeing).\n\nA spectrum was secured of this object, for a total of 4x600 s, starting \non Oct 1.299 UT (6.1 hr after the GRB). The continuum is consistent with \na stellar spectrum, and we conclude that this target is not associated \nwith GRB 161001A.\n\nOur slit, at a position angle of 319.6 deg (CCW from north), does \nhowever cover a portion of the XRT error circle. Within the wings of the \nthe PSF of the DSS object, approximately 0.8 arcsec SE, we detect a \nnumber of emission lines which are consistent with [O II], Hbeta, [O \nIII] and Halpha at a common redshift of z = 0.891, revealing the \npresence of a background object. While we cannot accurately determine \nits position from the slit information alone, that is consistent with \nbeing at the edge of the XRT error circle. Our images also hint a faint \nextension of the DSS object at a position consistent with that of the \nemission lines, which could represent the continuum emission of the \nobject. As such, this is a candidate host galaxy of GRB 161001A.\n\nWe caution that we have no way to confirm the association between the \nemission line object and the GRB. No variability can be inferred from \nour data, and as we lack an estimate of the continuum flux, we can not \npresently quantify the chance association probability.\n\nA finding chart showing the region surrounding the XRT position is shown \nat this URL: \nhttp://www.astro.ku.dk/~malesani/GRB/161001A/GRB161001A_slit.png\n\nWe acknowledge excellent support from the ESO observing staff at \nParanal, in particular Zahed Wahhaj, Jonathan Smoker, and Claudia Cid.",
  "circularId": 19971,
  "createdOn": 1475326635000,
  "email": "malesani@dark-cosmology.dk",
  "subject": "GRB 161001A: X-shooter spectroscopy, candidate host galaxy and redshift",
  "submitter": "Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>",
  "eventId": "GRB 161001A"
}