{
  "bibcode": "2006GCN..4695....1C",
  "body": "Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David\nW. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel\n(LBNL), J. Brinkmann (APO), Donald P. Schneider (PSU), and\nDaniel E. Vanden Berk (PSU) report:\n\nThe Sloan Digital Sky Survey (SDSS) imaged the field of burst\nGRB060206 prior to the burst.  As these data should be useful\nas a pre-burst comparison and for calibrating photometry,\nwe are supplying the images and photometry measurements for\nthis GRB field to the community.\n\nData from the SDSS, including 5 FITS images, 3 JPGS, and\n3 files of photometry and astrometry, are being placed at\nhttp://mizar.as.arizona.edu/~grb/public/GRB060206\n\nWe supply FITS images in each of the 5 SDSS bands of a 8'x8'\nregion centered on the GRB position (ra=202.946 (13:31:47.0),\ndec=35.0750 (35:04:30.0); GCN 4682), as well as 3 gri\ncolor-composite JPGs (with different stretches). The units\nin the FITS images are nanomaggies per pixel.  A pixel is\n0.396 arcsec on a side. A nanomaggie is a flux-density unit\nequal to 10^-9 of a magnitude 0 source or, to the extent that\nSDSS is an AB system, 3.631e-6 Jy.  The FITS images have WCS\nastrometric information.\n\nIn the file GRB060206_sdss.calstar.dat, we report photometry\nand astrometry of 346 bright stars (r<20.5) within 15' of the\nburst location.  The magnitudes presented in this file are asinh\nmagnitudes as are standard in the SDSS (Lupton 1999, AJ, 118,\n1406). Beware that some of these stars are not well-detected\nin the u-band; use the errors and object flags to monitor\ndata quality.\n\nIn the files GRB060206_sdss.objects_flux.dat and\nGRB060206_sdss.objects_magnitudes.dat, we report photometry\nof 771 objects detected within 6' of the GRB position.\nWe have removed saturated objects and objects with model\nmagnitudes fainter than 23.0 in the r-band.  The fluxes listed\nin GRB060206_sdss.objects_flux.dat are in nanomaggies while\nthe magnitudes listed in GRB060206_sdss.objects_magnitudes.dat\nare asinh magnitudes.\n\nAll quantities reported are standard SDSS photometry, meaning\nthat they are very close to AB zeropoints and magnitudes are\nquoted in asinh magnitudes.  Photometric zeropoints are known\nto about 2% rms.  None of the photometry is corrected for\ndust extinction.  The Schlegel, Finkbeiner, and Davis (1998)\npredictions for this region are A_U=0.054 mag, A_g=0.040 mag,\nA_r = 0.029 mag, A_i=0.022 mag, and A_z=0.015 mag.\n\nThere are currently no objects within 6 arcminutes of the GRB\nposition in the SDSS spectroscopic database.\n\nSDSS astrometry is generally better than 0.1 arcsecond per\ncoordinate.  Users requiring high precision astrometry should\ntake note that the SDSS astrometric system can differ from\nother systems such as those used in other notices; we have\nnot checked the offsets in this region.\n\nMore detailed information pertaining to our SDSS GRB releases\ncan be found in our initial data release paper (Cool et\nal. 2006, astro-ph/0601218).  See the SDSS DR4 documentation\nfor more details: http://www.sdss.org/dr4.\n\nThese data have been reduced using a slightly different\npipeline than that used for SDSS public data releases.\nWe cannot guarantee that the values here will exactly match\nthose in the data release in which these data are included.\nIn particular, we expect the photometric calibrations to differ\nby of order 0.01 mag.\n\nThis note may be cited, but please also cite the SDSS data\nrelease paper, Adelman-McCarthy et al. (2006, ApJS, in press,\nastro-ph/0507711), when using the data or referring to the\ntechnical documentation.",
  "circularId": 4695,
  "createdOn": 1139244628000,
  "email": "rcool@as.arizona.edu",
  "subject": "GRB060206: SDSS Pre-Burst Observations",
  "submitter": "Richard J. Cool at U.of AZ/Steward Obs  <rcool@as.arizona.edu>",
  "eventId": "GRB 060206"
}