{
  "bibcode": "2010GCN.10717....1S",
  "body": "P. Schady, F. Olivares, R. Filgas and J. Greiner (MPE Garching) report\non behalf of the GROND team:\n\nWe observed the field of GRB 100504A (Swift trigger 421124; Mao et\nal., GCN #10712) simultaneously in g'r'i'z'JHK with GROND (Greiner et\nal. 2008, PASP, 120, 405) mounted at the 2.2 m MPI/ESO telescope at La\nSilla Observatory (Chile).\n\nObservations started at 01:30 UT on May 5 (about 6.2 hours after the\nGRB trigger). They were performed at a high airmass.\n\nWe do not detect a source within the Swift UVOT-enhanced XRT error\ncircle (Mao et al. GCN #10713) in any of the GROND filters. Coadded\nimages of 24 min of integration in g'r'i'z' and 20 min in JHK yield\nthe following 3-sigma upper limits:\n\ng' > 23.2\nr' > 22.2\ni' > 21.6\nz' > 21.2\nJ > 19.4\nH > 19.1\nK > 18.9\n\nWe note the presence of two uncatalogued sources 3\" North-West of the\nenhanced XRT position with magnitudes r' = 19.8 and J = 18.0 for the\nmore southern of the two, and r' = 20.2 and J = 18.6 for the second\nsource. Observations are continuing.\n\nAll magnitudes given above are in the AB system and are based on the\nGROND zeropoints and 2MASS field stars. No correction has been applied\nfor the large, uncertain Galactic foreground extinction corresponding\nto a reddening of E_(B-V)~ 0.8 in the direction of the burst (Schlegel\net al. 1998).",
  "circularId": 10717,
  "createdOn": 1273036183000,
  "email": "felipe@mpe.mpg.de",
  "subject": "GRB 100504A: GROND Upper limits",
  "submitter": "Felipe Olivares Estay at MPE  <felipe@mpe.mpg.de>",
  "eventId": "GRB 100504A"
}