{
  "bibcode": "2017GCN.21244....1F",
  "body": "W. Fong, B. Rothberg, J. Hill, P. Milne, N. Smith and D. Zaritsky\n(University of Arizona) report on behalf of the AZTEC (Arizona Transient\nExploration and Characterization) team:\n\n\"We observed the field of the Fermi/LAT candidate (Omodei et al., GCN\n21227) with the Large Binocular Camera (LBC) mounted on the 2x8.4-meter\nLarge Binocular Telescope (LBT) on Mount Graham, Arizona beginning on 2017\nJun 10.156 UT (2.07 days post-trigger; LSC/Virgo et al. GCN 21221). We\nobtained 26x30-sec of i-band imaging in 1.7\" seeing at a mean airmass of\n2.2. The observations cover 88% of the Fermi/LAT localization region (90%\nconfidence; Omodei et al., GCN 21227), as well as the positions of\nSwift/XRT Sources 1-4 (Evans et al.; GCN 21233).\n\nInspection of the LBT observations relative to Pan-STARRS1 archival imaging\nreveals no new sources in or around the positions of XRT Sources 1-4.\nMoreover, photometry of the known optical sources are consistent with the\narchival PS1 and SDSS values within the 1-sigma uncertainties,\ncorroborating the conclusions from shallower imaging with NOWT (Xu et al.,\nGCN 21236) and Swift/UVOT (Emery et al., GCN 21235). Calibrated to SDSS\nstars in the field, we estimate a 3-sigma limiting magnitude of i_AB>22.4\nmag for the observations.\n\nWe thank LBT Director Christian Veillet for awarding this observing time.\"",
  "circularId": 21244,
  "createdOn": 1497144817000,
  "email": "wenfai@gmail.com",
  "subject": "LIGO/Virgo G288732: LBT optical imaging of the Fermi/LAT candidate",
  "submitter": "Wen-fai Fong at U of Arizona  <wenfai@gmail.com>",
  "eventId": "LIGO/Virgo G288732"
}