{
  "bibcode": "2021GCN.31000....1O",
  "body": "B. O'Connor (UMD, GWU),S.B. Cenko (UMD,NASA-GSFC),\nE. Troja (UMD, NASA-GSFC),A.Gottlieb (UMD,NASA-GSFC),\nS.Dichiara (PSU),A. Kutyrev (UMD,NASA-GSFC),\nS. Veilleux (UMD)\n\nWe observed the field of GRB 211023B (Dichiara et al., GCN 30960)\nusing the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery\nTelescope (LDT) at Happy Jack, AZ. Observations began on October 25,\n2021 at 11:42:14 UT (~1.61 d after the GRB), and were performed in\nr-band for a total of 18x150 s exposures under poor conditions.\n\nWe detect a source coincident with the position of the optical counterpart\nreported by UVOT (Kuin et al., GCN 30975) and CAHA (Kann et al., GCN 30992).\nWe measure a brightness of r~23 AB mag, brighter than the archival object\nreported by Pozanenko et al. (GCN 30972). We do not detect any other source\nwithin 5\" radius of the UVOT position with a 3-sigma upper limit r>24.0 mag.\n\nGiven the non-detection at ~15 hours (Watson et al., GCN 30973),\nour detection implies a shallow temporal decay index beta<0.6,\nassuming a power-law decline as F~t^-beta. While this may be due\nin part to the underlying source (Pozanenko et al., GCN 30972),\nwe note that the same flattening is also observed in X-rays by Swift/XRT.\nTherefore, we strongly encourage continued follow-up of this source.\n\nMagnitudes are calibrated against the SDSS catalog and are not corrected\nfor Galactic extinction.\n\nWe thank the staff of the Lowell Discovery Telescope for assistance\nwith these observations.",
  "circularId": 31000,
  "createdOn": 1635203472000,
  "email": "oconnorb@umd.edu",
  "subject": "GRB 211023B: LDT Optical Afterglow Detection",
  "submitter": "Brendan O'Connor at UMD  <oconnorb@umd.edu>",
  "eventId": "GRB 211023B"
}