{
  "bibcode": "2011GCN.11830....1L",
  "body": "G. Leloudas, D. Malesani (DARK/NBI), N.R. Tanvir (U. Leicester), Dong  \nXu (WIS), A.J. Levan (U. Warwick), P. Jakobsson (U. Iceland), T.  \nPursimo (NOT), report on behalf of a larger collaboration.\n\n\nWe used the Nordic Optical Telescope (La Palma, Spain) equipped with  \nALFOSC to observe the field of GRB 110328A / Swift J164449.3+573451  \n(Cummings et al., GCN 11823; Barthelmy et al., GCN 11824).  \nObservations started at 01:47 UT (12.8 and 12.1 hr after the first and  \nsecond trigger, respectively). We obtained 2x600 s in BVR and 4x300 s  \nin z.\n\nIn all filters we detect an object at the coordinates (J2000):\nRA: 16:44:50.0\nDEC: +57:34:59.13\nwith an astrometric calibration error of approximately 0.3 arcsec.\n\nThis position is within the enhanced XRT error circle (Osborne et al.,  \nGCN 11826) and is consistent with the coordinates of the object  \nreported by Cenko et al. (GCN 11827) from pre-outburst images.\n\nAt the moment we have no good photometric calibration of the field so  \nphotometry should be considered preliminary (see also GCN 11827).  \nAssuming R = R1 = 19.40 and B = B2 = 21.30 for  the USNO B1.0 star  \n1475-0312998, we estimate for the counterpart B = 24.0 +- 0.2 and R =  \n22.6 +- 0.05 (statistical errors only).\n\nAt this stage it is not possible to verify whether the source is  \nvariable.",
  "circularId": 11830,
  "createdOn": 1301381740000,
  "email": "giorgos@dark-cosmology.dk",
  "subject": "GRB 110328A / Swift J164449.3+573451: NOT optical observations.",
  "submitter": "Giorgos Leloudas at Dark Cosmology Centre  <giorgos@dark-cosmology.dk>",
  "eventId": "GRB 110328A"
}