{
  "bibcode": "2007GCN..6985....1P",
  "body": "S. Piranomonte (INAF/OAR), P. D'Avanzo (INAF/OABr), D. Malesani\n(DARK), A. Fernandez-Soto ( U.Valencia), G. Tagliaferri (INAF/OABr),\nG. Chincarini (U.Bicocca), S. Covino (INAF/OABr), F. Fiore (INAF/OAR),\nD. Fugazza (INAF/OABr), L. Stella (INAF/OAR), report on behalf of the\nMISTICI collaboration:\n\nWe observed the field of GRB 071021 (Sakamoto et al., GCN 6958) with the\n8.2m VLT+FORS2 equipped with the R filter (effective wavelength:\n6550 A; FWHM: 1650 A).\n\nAn eight-minute exposure was obtained on Oct 22.06688 , and a second,\nthirty-minute exposure, on Oct 22.99604. A weak source is detected in\nboth images at the position of the candidate afterglow provided by\nCastro-Tirado et al. (GCNs 6968, 6971).\n\nThe object has not faded significantly between both epochs, although\nthe very low S/N (~2) in the first image does not allow for a strong\nstatement regarding its variability.\n\nCombining our own data and all the available optical-NIR data (GCNs\n6962, 6973, 6974, 6975, 6976, 6980, 6983) we have measured a\nphotometric redshift z~5, but with a 2-sigma confidence interval that\nincludes all values in the z=[0 ... 5.5] range.\n\nAn alternative explanation for all the available data is that of a\nstrongly reddened afterglow (detected as a fading source in the H- and\nK-band images), having taken place in a galaxy at a significantly\nlower redshift (detected in our deeper, bluer, R- and z-band\nimages). This model should be checked via spectroscopy of the putative\nhost galaxy.\n\nOur R-band images and the results of the preliminary photometric\nredshift analysis are posted at:\n\nhttp://ayalga.uv.es/~fsoto/grb/grb071021/\n\nWe acknowledge excellent support from the ESO staff, in particular\nEmanuela Pompei and Hugues Sana.\n\nThis message may be cited.\n\n\n\n-------------------------------------------------\nThis mail sent through IMP: http://horde.org/imp/",
  "circularId": 6985,
  "createdOn": 1193257412000,
  "email": "piranomonte@mporzio.astro.it",
  "subject": "GRB 071021: R-band detection and analysis",
  "submitter": "Silvia Piranomonte at OAR  <piranomonte@mporzio.astro.it>",
  "eventId": "GRB 071021"
}