{
  "bibcode": "2017GCN.21249....1M",
  "body": "Tomoki Morokuma (The University of Tokyo), Masaomi Tanaka (National \nAstronomical Observatory of Japan), Nozomu Tominaga (Konan University),\nShigeyuki Sako, Ryou Ohsawa, Mamoru Doi, Kentaro Motohara (The \nUniversity of Tokyo) on behalf of J-GEM collaboration\n\nWe report optical imaging follow-up observations in an error region of \nthe possible electromagnetic counterpart of G288732 (GCN 21221) \ndiscovered with Fermi LAT (Omodei et al. 2017, GCN, 21227). We observed \nthe field with 1.05-m Kiso Schmidt telescope and its 2.2 deg x 2.2 deg \nfield-of-view camera, Kiso Wide Field Camera (KWFC; Sako et al. 2012, \nSPIE, 8446, 84466L). We took two consecutive 1-sec exposures twice in \ni-band on June 9.483, 9.489, 9.527, and 9.529, 2017 UT, roughly 123 ks \nafter the GW detection. The median depth of the images is 15.6 mag (AB, \n5 sigmas). Although there is a 1.5 arcmin gap in Declination because of \nthe spatial gap of the CCDs, we covered almost the entire error field of \nthe possible Fermi LAT detection. We compared the detected source \ncatalogs with the public Pan-STARRS1 catalog (Chambers et al. 2016, \narXiv:1612.05560) and do not find any new transient sources within the \nFermi LAT error circle.  All the seven Swift XRT sources reported\nin Evans et al. (2017, GCN 21233) were covered by our observations and\nthe source 7 is detected in our images with almost constant brightness\nof i=12.8 mag.\n\n[GCN OPS Note(14jun17): Per author's request, the phase\n\"were covered by our observations\" was added to the last sentence.]",
  "circularId": 21249,
  "createdOn": 1497266782000,
  "email": "tmorokuma@ioa.s.u-tokyo.ac.jp",
  "subject": "LIGO/Virgo G288732: Kiso/KWFC optical imaging of the possible Fermi/LAT counterpart",
  "submitter": "Tomoki Morokuma at U.TokyoJ-GEM  <tmorokuma@ioa.s.u-tokyo.ac.jp>",
  "eventId": "LIGO/Virgo G288732"
}