{
  "bibcode": "2013GCN.14408....1M",
  "body": "A. N. Morgan (UC Berkeley) reports:\n\nWe observed the field of GRB 130420A (Page et al., GCN 14406) with the 1.3m\nPAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2013-Apr-20\n07h37m23s UT, 8.9 minutes after the Swift Trigger.  In  mosaics (effective\nexposure time of ~10 minutes) taken simultaneously in the J, H, and Ks\nfilters, we detect the optical afterglow (Guidorzi et al., GCN 14405; Page\net al., GCN 14406; Guver et al., GCN 14407).\n\nThe preliminary photometry yields:\n\npost burst\nt_mid (hr) exp.(m)  filt  mag   m_err\n0.28       9.75     J     15.59  0.05\n0.28       9.75     H     14.99  0.07\n0.28       9.75     Ks    14.13  0.12\n\nObservations are ongoing. All magnitudes are given in the Vega system,\ncalibrated to 2MASS. No correction for Galactic extinction has been made to\nthe above reported values.",
  "circularId": 14408,
  "createdOn": 1366445810000,
  "email": "qmorgan@gmail.com",
  "subject": "GRB 130420A: PAIRITEL NIR detections",
  "submitter": "Adam Morgan at U.C. Berkeley  <qmorgan@gmail.com>",
  "eventId": "GRB 130420A"
}