{
  "bibcode": "2020GCN.29208....1B",
  "body": "S. Belkin (IKI), A. Pozanenko (IKI), M. Krugov (FAI), P. Minaev (IKI) \nreport on behalf of GRB IKI FuN collaboration:\n\nWe observed the field of XRT 1-3 sources (D'Elia et al., GCN 29202)\n(hereafter X1,X2,X3) found in IPN localization area (Svinkin et al.,\nGCN 29182) of GRB 201227A (Ursi et al., GCN 29179; Xiao et al., GCN\n29187; Svinkin et al., GCN 29196; Lesage et al., GCN 29206) with\nChilescope RC-1000 starting on 2020-12-29 (UT) 04:02:05 in r'-filter.\n\nThe X3 source was observed by one 300 s exposure, and the filed of X1,X2\nwas observed by 3*300 s exposure. The limiting magnitude of single\nexposure of X3 and the stacked 3*300 s exposure is about r'=20.9.\n\nThere are two optical sources close or on the edge of the XRT error \ncircle localization of X3. Both sources are present in USNO-B1.0 and our \nphotometry of the sources show no excess in brightness in comparison\nwith any R-mag of USNO-B1.0.\n\nAlso there are two optical sources close or on the edge of the XRT error\ncircle localization of X1. Both source are also present in USNO-B1.0 and\nour photometry of the sources show no excess in brightness in comparison\nwith any R-mag of USNO-B1.0.\n\nAt the edges of X2 error circle we found two sources which not presented\nin USNO-B1.0. The coordinates of the first one (X2_O1) is RA(J2000)=11h \n22m 29.34s, Dec(J2000)=-73d 28��� 44.9������. The photometry of the source is \nr'= 20.50 +/-0.29 and the source is barely visible in DSS2 plate. The \ncoordinates of second one (X2_02) is RA(J2000)=11h 22m 27.94s, \nDec(J2000)=-73d 28��� 50.6������. The photometry of the source is r'= 20.52 \n+/-0.29 and the source is not presented in DSS2 plate. We may suggest \nthe optical object X2_02 could be a counterpart of GRB 201227A.\n\nThe photometry is based on nearby stars from the APASS_DR8 and still\npreliminary\n\nRA DEC r\n11:19:31.40904 -73:35:47.6880 14.090\n11:19:44.89128 -73:34:49.6092 15.180\n11:19:36.65304 -73:36:30.2112 15.307\n\nTaking into account that early more deep observations of the IPN field \nby GRAWITA VST-ESO PARANAL (Izzo et al., GCN 29207) does no show any \ncounterpart we  may suggest the X2_O2 source (RA(J2000)=11h 22m 27.936s, \nDec(J2000)=-73d 28��� 50.55������) is a possible optical counterpart or \nkilonova of GRB 201227A.",
  "circularId": 29208,
  "createdOn": 1609362842000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 201227A: Chilescope optical observations, possible optical counterpart",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 201227A"
}