{
  "body": "D. Xu, S.Y. Fu, S.Q. Jiang, Z.P. Zhu (NAOC), Z. Gray (NOT), report:\n\nWe observed the field of GRB 230728A detected by Swift (Salvaggio et al., GCN 34282) using the the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 04:26:55 UT on 2023-07-28, i.e., ~ 1.61 hr after the Swift/BAT trigger, and 3x300 s Sloan r-filter images and 5x200 s Sloan z-filter images were obtained, respectively.\n\nNo optical source is detected within or at the border of the Swift/XRT error circle (radius ~1.9 arcsec, 90% containment, Salvaggio et al., GCN 34282) down to upper limits of r > 24.2 mag (5-sigma) and z > 23.0 mag (5-sigma).\n\nWe note that there exists a galaxy south-western, ~3.7 arcsec away from the center of the Swift/XRT error circle. This galaxy is present in SDSS with r ~ 22.39 mag, z ~ 22.99 mag, z_phot ~ 0.34, and in Legacy Survey with r ~ 22.14 mag, z ~ 22.04 mag, z_phot ~ 0.37, respectively. Preliminary photometry of the galaxy from the NOT data gives r ~ 22.4 mag and z ~ 23.0 mag, which are consistent with the above archival values, indicating that there is no prominent optical afterglow in this potential host galaxy.\n\n\n",
  "createdOn": 1690536186077,
  "eventId": "GRB 230728A",
  "submittedHow": "email",
  "bibcode": "2023GCN.34285....1X",
  "submitter": "Dong Xu at NAOC/CAS <dxu@nao.cas.cn>",
  "subject": "GRB 230728A: NOT optical observations and possible host galaxy",
  "circularId": 34285
}