{
  "bibcode": "2009GCN.10113....1C",
  "body": "B. E. Cobb (UC Berkeley) reports:\n\nUsing the ANDICAM instrument on the 1.3m telescope at CTIO, we\nobtained optical/IR imaging of the error region of GRB 090926a\n(GCN 9933, Bissaldi et al.) over several epochs.  For each epoch,\ntotal summed exposure times amounted to 36 minutes in I and\n30 minutes in J.\n\nThe afterglow of GRB 090926a (e.g. GCN 9937, Haislip et al.;\nGCN 9938, Gronwall et al.) is detected in our images with\nthe following magnitudes (calibrated using Landolt standard stars\nin the optical and 2MASS stars in the IR):\n\ntime\npost-burst      I mag           J mag\n20.60 hrs       18.17+/-0.06    17.28+/-0.07\n71.74 hrs       19.53+/-0.07    18.35+/-0.09\n119.18 hrs      20.33+/-0.10    19.16+/-0.13\n\nBetween ~21 and 119 hours post-burst, the afterglow fades\nwith a rate of alpha ~ -1.1+/-0.1 (where afterglow flux is\nproportional to t^alpha).",
  "circularId": 10113,
  "createdOn": 1256887645000,
  "email": "bcobb@astro.berkeley.edu",
  "subject": "GRB 090926a, SMARTS optical/IR afterglow observations",
  "submitter": "Bethany Cobb at UC Berkeley  <bcobb@astro.berkeley.edu>",
  "eventId": "GRB 090926A"
}