{
  "bibcode": "2005GCN..4353....1C",
  "body": "Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David\nW. Hogg (NYU), and Michael R. Blanton (NYU) report on behalf of\nthe Sloan Digital Sky Survey (SDSS) Collaboration:\n\nThe Sloan Digital Sky Survey (SDSS) imaged the field of burst\nGRB051215 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/GRB051215\n\nWe supply FITS images in each of the 5 SDSS bands of a 8'x8' region\ncentered on the GRB position (ra=163.139 (10:52:33.4), dec=38.6260\n(38:37:33.6); GCN 4352), as well as 3 gri color-composite JPGs (with\ndifferent stretches). The units in the FITS images are nanomaggies\nper pixel.  A pixel is 0.396 arcsec on a side. A nanomaggie is\na flux-density unit equal to 10^-9 of a magnitude 0 source or,\nto the extent that SDSS is an AB system, 3.631e-6 Jy.  The FITS\nimages have WCS astrometric information.\n\nIn the file GRB051215_sdss.calstar.dat, we report photometry\nand astrometry of 179 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 GRB051215_sdss.objects_flux.dat and\nGRB051215_sdss.objects_magnitudes.dat, we report photometry\nof 1240 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 GRB051215_sdss.objects_flux.dat are in nanomaggies while the\nmagnitudes listed in GRB051215_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=0.081 mag, A_g=0.059 mag, A_r = 0.043 mag, A_i=0.033\nmag, and A_z=0.023 mag.\n\nThe file GRB051215_sdss.spectro.dat contains a list of the 8 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\nAmong the spectra, there are 4 galaxies at the same redshift z=0.145.\nMost likely, this is the redshift of the cluster noted in Ofek and Gal-Yam\n(GCN 4351).  This value is somewhat higher than photometric redshift\nestimate of z=0.09 in Gal et al. (2003, AJ, 125, 2064), although there\nare also 2 galaxies near that redshift.\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\n\nThese data have been reduced using a slightly different pipeline\nthan that used for SDSS public data releases.  We cannot guarantee\nthat the values here will exactly match those in the data release\nin which these data are included.  In particular, we expect the\nphotometric calibrations to differ by of order 0.01 mag.\n\nThis note may be cited, but please also cite the SDSS data release\npaper, Abazajian et al.  (AJ, 129, 1755, 2005), when using the data\nor referring to the technical documentation.",
  "circularId": 4353,
  "createdOn": 1134616165000,
  "email": "rcool@as.arizona.edu",
  "subject": "GRB051215 - SDSS pre-burst observations",
  "submitter": "Richard J. Cool at U.of AZ/Steward Obs  <rcool@as.arizona.edu>",
  "eventId": "GRB 051215"
}