{
  "bibcode": "2015GCN.17829....1X",
  "body": "Dong Xu (NAOC/CAS), Xue-Bing Wu, Qian Yang (PKU) report\n\nWe observed the field of the XRT transient (Sbarufatti et al., GCN\n17827), which is very likely the X-ray counterpart of GRB 150518A\n(Kawamuro et al., GCN 17825) , using the 2.16m telescope located at\nXinglong, Hebei, China. Observations started at 14:23:06 UT (i.e.,\n16.68 hr after the burst) in a rather poor seeing of 3\", and 4x300s\nR-band frames were obtained.\n\nAt the XRT-UVOT enhanced position (R.A. = 15:36:48.25, Dec. =\n+16:19:47.3 , Err. Rad: = 2.2������), an optical source is well detected\nat m(R) = 20.3 +/- 0.2 mag, calibrated with nearby SDSS stars. The\nsource largely looks round in our stacked image.\n\nWe note that there exists a source at the XRT-UVOT position that is\nalready detected and classified as a galaxy by SDSS (u=22.88, g=22.14,\nr=21.43, i=21.24, z=20.74), with a photometric redshift of z_ph=0.35\n+/- 0.11. The Xinglong detection is brighter than the SDSS detection\nby about 1 magnitude in the R/r filters, and we thus think that it is\nthe optical afterglow of the GRB. If the afterglow is indeed\nassociated with the galaxy at such a redshift, it would be doable to\nsearch for a GRB-associated supernova.\n\nWe thank Junjun Jia for carrying out these observations.",
  "circularId": 17829,
  "createdOn": 1432077960000,
  "email": "dong.dark@gmail.com",
  "subject": "GRB 150518A: Xinglong2.16m optical afterglow detection",
  "submitter": "Dong Xu at NAOC/CAS  <dong.dark@gmail.com>",
  "eventId": "GRB 150518A"
}