{
  "bibcode": "2009GCN..9319....1O",
  "body": "F. Olivares, T. Kruehler, J. Greiner (all MPE Garching) report on behalf of\nthe GROND team: \n\nWe observed the central area of the error box of GRB 090427 localized by the\nIPN (Pal'shin et al., GCN #9277) simultaneously in g'r'i'z'JHK with GROND\nmounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile).\nThree adjacent pointings centered at \n\nRA = 15,43,31.0  Decl. = -13,40,00\nRA = 15,43,43.4  Decl. = -13,30,00 (center of IPN box)\nRA = 15,43,55.0  Decl. = -13,20,00 \n\nhave been observed with our 10x10 arcmin (in JHK) and 5.4x5.4 arcmin\n(g'r'i'z') field-of-view, thus covering about 27% and 8% of the full error\nbox respectively (see sketch at http://www.mpe.mpg.de/~jcg/grb090427.html). \n\nObservations started on 29 Apr. 2009 at 06:20 UT, 30.9 h after the burst,\nand consisted, for each of the three fields, of a set of images with a\ntotal integration time of 8 min in JHK and 7.7 min in g'r'i'z'. A second\nepoch of all three fields was obtained on 30 Apr. 2009 starting at 05:18 UT. \n\nImage subtraction of the two epochs does not reveal a variable source\nin any of the three fields, down to limiting magnitudes (all in AB system) \nof \n\ng' > 23.9\nr' > 23.8\ni' > 23.5\nz' > 23.2\nJ > 22.2\nH > 21.7\nK > 20.6 \n\nThese magnitudes have been obtained using 2MASS field stars and the GROND\nzeropoints as reference.",
  "circularId": 9319,
  "createdOn": 1241395634000,
  "email": "felipe@mpe.mpg.de",
  "subject": "GRB 090427: GROND observations",
  "submitter": "Felipe Olivares Estay at MPE  <felipe@mpe.mpg.de>",
  "eventId": "GRB 090427"
}