{
  "bibcode": "2006GCN..5679....1C",
  "body": "Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona),\nDavid W. Hogg (NYU), Michael R. Blanton (NYU), David\nJ. Schlegel (LBNL), J. Brinkmann (APO), Donald Q. Lamb\n(Chicago), Donald P. Schneider (PSU), and Daniel E. Vanden\nBerk (PSU) report:\n\nThe Sloan Digital Sky Survey (SDSS) imaged the field of\nburst GRB061002 prior to the burst.  As these data should\nbe useful as a pre-burst comparison and for calibrating\nphotometry, we are supplying the images and photometry\nmeasurements for this 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\nat http://mizar.as.arizona.edu/~grb/public/GRB061002\n\nWe supply FITS images in each of the 5 SDSS bands of a\n8'x8' region centered on the GRB position (ra=220.346\n(14:41:23.0), dec=48.7360 (48:44:09.6); BAT Trigger\n231974), as well as 3 gri color-composite JPGs (with\ndifferent stretches). The units in the FITS images are\nnanomaggies per pixel.  A pixel is 0.396 arcsec on a\nside. A nanomaggie is a flux-density unit equal to 10^-9\nof a magnitude 0 source or, to the extent that SDSS is\nan AB system, 3.631e-6 Jy.  The FITS images have WCS\nastrometric information.\n\nIn the file GRB061002_sdss.calstar.dat, we report\nphotometry and astrometry of 226 bright stars (r<20.5)\nwithin 15' of the burst location.  The magnitudes presented\nin this file are asinh magnitudes as are standard in the\nSDSS (Lupton 1999, AJ, 118, 1406). Beware that some of\nthese stars are not well-detected in the u-band; use the\nerrors and object flags to monitor data quality.\n\nIn the files GRB061002_sdss.objects_flux.dat and\nGRB061002_sdss.objects_magnitudes.dat, we report photometry\nof 371 objects detected within 6' of the GRB position.\nWe have removed saturated objects and objects with\nmodel magnitudes fainter than 23.0 in the r-band.\nThe fluxes listed in GRB061002_sdss.objects_flux.dat\nare in nanomaggies while the magnitudes listed in\nGRB061002_sdss.objects_magnitudes.dat are asinh magnitudes.\n\n\n\nAll quantities reported are standard SDSS photometry,\nmeaning that they are very close to AB zeropoints\nand magnitudes are quoted in asinh magnitudes.\nPhotometric zeropoints are known to about 2% rms.\nNone of the photometry is corrected for dust extinction.\nThe Schlegel, Finkbeiner, and Davis (1998) predictions\nfor this region are A_U=0.223 mag, A_g=0.164 mag, A_r =\n0.119 mag, A_i=0.090 mag, and A_z=0.064 mag.\n\nThere are currently no objects within 6 arcminutes of the\nGRB position in the SDSS spectroscopic database.\n\n\nSDSS astrometry is generally better than 0.1 arcsecond\nper coordinate.  Users requiring high precision astrometry\nshould take note that the SDSS astrometric system can\ndiffer from other systems such as those used in other\nnotices; we have not checked the offsets in this region.\n\nMore detailed information pertaining to our SDSS GRB\nreleases can be found in our initial data release paper\n(Cool et al. 2006, astro-ph/0601218).  See the SDSS DR4\ndocumentation for more details: http://www.sdss.org/dr5.\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\ndiffer by 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, 162,\n38), when using the data or referring to the technical\ndocumentation.",
  "circularId": 5679,
  "createdOn": 1159762198000,
  "email": "rcool@as.arizona.edu",
  "subject": "GRB061002 - SDSS Pre-Burst Observations",
  "submitter": "Richard J. Cool at U.of AZ/Steward Obs  <rcool@as.arizona.edu>",
  "eventId": "GRB 061002"
}