{
  "bibcode": "2005GCN..4399....1C",
  "body": "Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David\nW. Hogg (NYU), Michael R. Blanton (NYU), J. Brinkmann (Apache\nPoint Observatory), Donald P. Schneider (PSU), and Daniel E. Vanden Berk\n(PSU) report on behalf of the Sloan Digital Sky Survey (SDSS)\nCollaboration:\n\nThe Sloan Digital Sky Survey (SDSS) imaged the field of burst\nGRB051227 prior to the burst.  As these data should be useful\nas a pre-burst comparison and for calibrating photometry, we are\nsupplying the images and photometry measurements for this GRB field\nto 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/GRB051227\n\nWe supply FITS images in each of the 5 SDSS bands of a 8'x8'\nregion centered on the GRB position (ra=125.270 (08:21:04.8),\ndec=31.9290 (31:55:44.4); Swift-BAT TRIGGER 174738), as well as 3\ngri color-composite JPGs (with different stretches). The units in\nthe FITS images are nanomaggies per pixel.  A pixel is 0.396 arcsec\non a side. A nanomaggie is a flux-density unit equal to 10^-9 of\na magnitude 0 source or, to the extent that SDSS is an AB system,\n3.631e-6 Jy.  The FITS images have WCS astrometric information.\n\nIn the file GRB051227_sdss.calstar.dat, we report photometry\nand astrometry of 825 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 in\nthe u-band; use the errors and object flags to monitor data quality.\n\nIn the files GRB051227_sdss.objects_flux.dat and\nGRB051227_sdss.objects_magnitudes.dat, we report photometry\nof 2481 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 GRB051227_sdss.objects_flux.dat are in nanomaggies while the\nmagnitudes listed in GRB051227_sdss.objects_magnitudes.dat are\nasinh magnitudes.\n\nAll quantities reported are standard SDSS photometry, meaning that\nthey are very close to AB zeropoints and magnitudes are quoted\nin asinh magnitudes.  Photometric zeropoints are known to about\n2% rms.  None of the photometry is corrected for dust extinction.\nThe Schlegel, Finkbeiner, and Davis (1998) predictions for this\nregion are A_U=0.213 mag, A_g=0.157 mag, A_r = 0.114 mag, A_i=0.086\nmag, and A_z=0.061 mag.\n\nThe file GRB051227_sdss.spectro.dat contains a list of the 4 objects\nwith SDSS spectroscopy within 6 arcminutes of the GRB position.\nIn addition to the redshift and 1-sigma error for each object,\nthis file also lists the object spectroscopic classification.\n\nSDSS astrometry is generally better than 0.1 arcsecond per\ncoordinate.  Users requiring high precision astrometry should take\nnote that the SDSS astrometric system can differ from other systems\nsuch as those used in other notices; we have not checked the offsets\nin this region.\n\nSee the SDSS DR4 documentation for more details:\nhttp://www.sdss.org/dr4",
  "circularId": 4399,
  "createdOn": 1135719371000,
  "email": "rcool@as.arizona.edu",
  "subject": "GRB051227: SDSS pre-burst observations",
  "submitter": "Richard J. Cool at U.of AZ/Steward Obs  <rcool@as.arizona.edu>",
  "eventId": "GRB 051227"
}