{
  "bibcode": "2013GCN.14449....1P",
  "body": "D. A. Perley (Caltech) reports on behalf of a larger collaboration:\n\nThe Palomar 60-inch telescope automatically responded to GRB 130427A \n(Maselli et al., GCN 14448) and began taking observations at 07:52:22 UT \n(4.42 minutes after the BAT trigger).  A series of 60-second images were \ntaken in r, i, and z filters; observations are still ongoing. Inspection \nof individual frames shows no detection of an optical transient \nconsistent with the XRT position to approximately r > 20.6 mag, i > 20.7 \nmag, z > 19.7 mag.\n\nNondetection of an afterglow in rapidly-triggered P60 observations is \nunusual (Cenko et al. 2009, ApJ 693, 1484), especially in the presence \nof an very bright GRB and early XRT afterglow.  This is suggestive of a \nhighly extinguished (or possibly high-redshift) burst, and may indicate \nthat the possible UVOT source reported by Maselli et al. was spurious. \nFurther observations, especially in the NIR, are strongly encouraged.",
  "circularId": 14449,
  "createdOn": 1367051949000,
  "email": "dperley@astro.caltech.edu",
  "subject": "GRB 130427A: P60 early nondetection",
  "submitter": "Daniel Perley at Caltech  <dperley@astro.caltech.edu>",
  "eventId": "GRB 130427A"
}