{
  "bibcode": "2010GCN.10572....1U",
  "body": "Adria Updike (Clemson University), Paulo Afonso, and Jochen Greiner (both\nMPE Garching) report on behalf of the GROND team:\n\nWe observed the field of GRB 100331B (SuperAGILE; Del Monte et al., GCN\n#10560) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory \n(Chile). Observations started at 09:31 UT on April 1, 2010, 12.37 hours after \nthe GRB trigger, and a second epoch was taken beginning at 08:50 UT on April\n2. They were performed at an average seeing of 1.0\" and at an average\nairmass of 1.3.\n\nWe do not detect a source within the Swift-XRT error circle reported by\nD'Elia et al. (GCN #10562).  Upper limits from the first epoch are limited\nto the NIR bands; the GROND observation was executed prior to the Swift/XRT\nobservation, and the XRT position turned out to be outside the FOV of our\noptical channels.\n\nOn April 1, our upper limits were:\nJ > 21.5,\nH > 21.0,\nK > 20.2\nfrom a total of 960 seconds of exposure time.\n\nOn April 2, our upper limits were:\ng' > 24.6,\nr' > 25.1,\ni' > 24.5,\nz' > 24.4,\nJ  > 22.6,\nH  > 22.1 and\nK  > 20.9\nfrom a total of 2952 seconds of exposure in the optical bands and 2320\nseconds in the NIR.\n\nThese limits are derived based on calibrating the images against GROND\nzeropoints and 2MASS field stars and are not corrected for the Galactic\nforeground extinction corresponding to a reddening of E_(B-V)= 0.12 in the\ndirection of the burst (Schlegel et al. 1998).",
  "circularId": 10572,
  "createdOn": 1270291230000,
  "email": "jcg@mpe.mpg.de",
  "subject": "GRB 100331B: GROND Upper limits",
  "submitter": "Jochen Greiner at MPI  <jcg@mpe.mpg.de>",
  "eventId": "GRB 100331B"
}