{
  "bibcode": "2017GCN.21003....1C",
  "body": "B. E. Cobb (GWU), reports:\n\nUsing the ANDICAM instrument on the 1.3m telescope at CTIO, we\nobtained optical/IR imaging of the error region of GRB 170405A\n(GCN 20984, Troja et al.) at two epochs (with mid-exposure times\nof 2017-04-06 02:51 UT & 06:52 UT). For each epoch, several\ndithered images were obtained with total summed exposure times\nof 15 min in V and I and 12 min in J and K.\n\nThe fading afterglow of GRB 170405A (e.g. GCN 20984, Troja et al.;\nGCN 20988, Malesani et al.; GCN 20989, Klotz et al.) was detected\nwith the preliminary magnitudes (or 3-sigma limits) listed below.\nNote that the optical photometry is calibrated against USNO-B1.0\nstars in the field, so suffers from a large photometric calibration\nerror of about +/-0.2 magnitudes, which has not been included in\nthe errors quoted below. The IR photometry is calibrated against\n2MASS stars. Additionally, the nearby source noted by Malesani\net al. (GCN 20988) is seen and is likely affecting the afterglow\nphotometry due to its proximity.\n\nmid-exposure\ntime post-burst\n(hours)     I mag          J mag     K mag\n8.19000    20.4+/-0.1   >18.5     >16.9\n12.1975    21.1+/-0.1   >18.8     >16.8",
  "circularId": 21003,
  "createdOn": 1491698106000,
  "email": "bcobb@gwu.edu",
  "subject": "GRB 170405A: SMARTS optical/IR afterglow observations",
  "submitter": "Bethany Cobb at GWU  <bcobb@gwu.edu>",
  "eventId": "GRB 170405A"
}