{
  "bibcode": "2021GCN.31038....1S",
  "body": "T. Sakamoto (AGU), G.S.H. Paek (SNU), Y. Urata (NCU),\nE. Troja (NASA/GSFC), M. Im (SNU), K. Aoki (NAOJ)\nreport on behalf of Subaru GRB team:\n\nWe observed the field of GRB 211023B (Dichiara et al., GCN Circ. 30960)\nwith Hyper Suprime-Cam (HSC) on the Subaru 8.2 m telescope starting from\n13:36 on October 28 about 4.7 days after the trigger.  Observations were\nperformed in the r filter for a total of 4800 s (32 x 150 s) exposure.\n\nAt a position consistent with the UVOT localization (Kuin & Dichiara, GCN Circ. 30975)\nand the Legacy Survey object (Pozanenko et al. GCN 30972), we detect an optical\nsource with magnitude r~23.6 AB. Since the source appears clearly extended in our images\nand its brightness is consistent with the Gemini-North observation (Rastinejad et al., GCN Circ. 31002),\narchival HSC g-band images of March 2016, and CFHT archival r-band images of September 2020,\nwe conclude that the source detected by Subaru is dominated by the host galaxy contribution,\nin agreement with Rastinejad et al. (GCN Circ. 31002).\n\nWe would like to thank the Subaru director, Dr. Michitoshi Yoshida for\napproving our ToO, and Dr. Tsuyoshi Terai and Dr. Ichi Tanaka for supporting\nour observation.",
  "circularId": 31038,
  "createdOn": 1636022529000,
  "email": "tsakamoto@phys.aoyama.ac.jp",
  "subject": "GRB 211023B: Subaru optical observation",
  "submitter": "Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>",
  "eventId": "GRB 211023B"
}