{
  "circularId": 12387,
  "email": "pmv@raunvis.hi.is",
  "submitter": "Paul Vreeswijk at U of Iceland  <pmv@raunvis.hi.is>",
  "bibcode": "2011GCN.12387....1V",
  "editedOn": 1731008492225,
  "body": "Paul Vreeswijk (U. Iceland), Daniele Malesani, Antonio de Ugarte\nPostigo (DARK, NBI), Dong Xu (WIS), Páll Jakobsson, Steve Schulze\n(U. Iceland) and Nial Tanvir (U. Leicester) report on behalf of a\nlarger collaboration:\n\nUsing ALFOSC on the Nordic Optical Telescope (NOT) we have obtained\nSloan r'- (3 x 600 s) and z'-band (6 x 300 s) imaging of the field of\nGRB 110921A (Baumgartner et al., GCN 12373, Barthelmy et al., GCN\n12383), starting on 2011 September 21.925 UT (roughly 8.3 hr after the\nburst). The observations were performed through clouds, but under good\nseeing conditions (~0.8\").\n\nWe do not detect the optical afterglow reported by Xin et al. (GCN\n12377, see also Xu et al., GCN 12385), or any other object within the\nenhanced Swift-XRT error circle (Goad et al., GCN 12379), down to\nlimiting magnitudes of about r'=23.3 and z'=21.0 (calibrated against\nthe SDSS catalog).\n\nJust outside the enhanced XRT error circle, at R.A.(J2000)\n19:36:23.38, decl.(J2000) 36:19:42.1 (with an uncertainty of 0.23\"),\nwe detect an r'=22.4+-0.2 source, also visible - albeit barely - in\nthe combined z'-band imaging. This apparent point source is\nconsistent, both in position and brightness, with the SDSS object\nnoted by Xu et al. (GCN 12385).\n\nWe are grateful for the NOT staff, particularly Fatemeh Sadat Kiaeerad\nand Marjaana Lindborg, for obtaining these observations.",
  "subject": "GRB 110921A: NOT observations",
  "eventId": "GRB 110921A",
  "format": "text/plain",
  "createdOn": 1316707890000,
  "editedBy": "Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>",
  "version": 2
}