{
  "bibcode": "2013GCN.14830....1P",
  "body": "D. A. Perley (Caltech) and S. B. Cenko (GSFC) report:\n\nThe Palomar 60-inch telescope automatically responded to GRB 130609A \n(Cummings et al., GCN 14828) and began taking observations at 04:03:23 \nUT (58.25 minutes after the BAT trigger) as soon as the sky became dark. \n  A sequence of cycled 60-second r, i, and z images was acquired.  We \ndetect no source consistent with the XRT localization in either \nindividual images or in combined stacks of the first 6 images in each \nfilter.  Approximate 5-sigma limiting magnitudes from the combined \nimages at an approximate mean time of 4:20 UT (75 minutes after the GRB \ntrigger) are:\n\nr > 22.5\ni > 21.5\nz > 20.9\n\nThese limits are suggestive of a dark GRB.  Cummings et al. report a \ndetection of significant excess absorption in the XRT spectrum, which \nmay indicate a dust-extinguished (as opposed to high-redshift) event, \nalthough given the quoted errors there the excess may be only marginal.\n\nNIR follow-up is highly encouraged.",
  "circularId": 14830,
  "createdOn": 1370755734000,
  "email": "dperley@astro.caltech.edu",
  "subject": "GRB 130609A: P60 nondetection",
  "submitter": "Daniel Perley at Caltech  <dperley@astro.caltech.edu>",
  "eventId": "GRB 130609A"
}