{
  "bibcode": "2005GCN..3506....1C",
  "body": "B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS \nconsortium, report:\n \nUsing the ANDICAM instrument on the 1.3m telescope at CTIO, we\nobtained simultaneous optical/IR imaging of the error region of\nGRB 050525a (Band et al. GCN 3466). Several dithered images were obtained\nin each filter, with total summed exposure times of 180s in each of BRIYJK \nand 120s in each of H and V.  Imaging was carried out in a symmetrical \nmanner so that the mid-exposure time is the same for all final combined \nimages, in this case being ~5.2 hours post-burst (2005-05-25 05:13 UT). \n \nThe afterglow reported by Rykoff et al. (GCNs 3465, 3468) is detected in \neach summed image, though the source appears only slightly above the \nbackground.  Preliminary comparison with USNO B1.0 stars in the optical \nand 2MASS stars in the IR yields the following approximate afterglow magnitudes:\n \n filter          AG mag\n ------          ------\n B               18.8+/-0.4\n R               18.1+/-0.3\n I               18.8+/-0.3\n \n J               17.4+/-0.3\n H               16.6+/-0.3\n K               16.15+/-0.35\n \nFurthermore, a second epoch of imaging was obtained at a mid-exposure time \nof ~53.4 hours post-burst (2005-05-27 05:27 UT).  Total summed exposure \ntimes for these images was 36 min in I and 30 min in J.  The afterglow \nexperienced significant decay between epochs and is not detectable in the \nsecond epoch images to a limiting magnitude of I > 21.2+/-0.2 \nand J > 18.8+/-0.1.",
  "circularId": 3506,
  "createdOn": 1117572324000,
  "email": "cobb@astro.yale.edu",
  "subject": "GRB 050525a, SMARTS optical/IR afterglow observations",
  "submitter": "Bethany Cobb at Yale U  <cobb@astro.yale.edu>",
  "eventId": "GRB 050525A"
}