{
  "bibcode": "2011GCN.12037....1X",
  "body": "D. Xu (WIS), S. Schulze, P. Jakobsson (U. Iceland), T. Pursimo (NOT),\nreport on behalf of a larger collaboration:\n\nWe continued to observe the field of GRB 110520A (De Pasquale et al.,\nGCN 12020) with the Nordic Opitcal Telescope (NOT) equipped with\nALFOSC. We obtained 6x300 s R-band images, starting at 23:02:40.4 UT\non May 21 (i.e., 26.565 hrs after the burst).\n\nThere was nothing visible within the enhanced XRT error circle\n(Osborne et al., GCN 12027). The optical source identified in our\nprevious imaging (Schulze et al., GCN 12025) is ~1.9\" northeast away\nof the center of the enhanced XRT error circle, which has a radius of\n1.5\" (90% C.L.). The source is still point-like and has R=23.7+/-0.1\nmag, same as our previous measurement.\n\nThe optical source noted by Levan et al. (GCN 12026) was clearly\ndetected in our previous imaging. It was largely point-like and had\nR=23.9+/-0.1 mag, calibrated with the #1464-0205280 star (R1=18.97,\nR2=18.92) in the USNO B1 catalog. Now it has become extended (about\n3.5\" southeast away of the center of the enhanced XRT error circle)\nand decayed to R=24.5+/-0.2 mag.",
  "circularId": 12037,
  "createdOn": 1306028856000,
  "email": "dong.xu@weizmann.ac.il",
  "subject": "GRB 110520A: NOT optical follow-ups",
  "submitter": "Dong Xu at Weizmann Inst  <dong.xu@weizmann.ac.il>",
  "eventId": "GRB 110520A"
}