Welcome to the GRAPES Data Release WWW pages

The data reduction process if described in Pirzkal et al., 2004. Two different extraction widths were used when extracting the spectra. The final data products are currenly in two sub-directories named 14th (wider extraction ) and 15th (narrower extraction).

In each of the following directories, the following files are available:
  • A_SPC.???.fits Combined spectra corresponding to PA ???
  • A_SPC.???.c.fits Combined spectra for PA??? with recomputed CONTAM column (in %)
  • A_SPC.???.cn.fits Combined spectra for PA??? with new CONTAM AND new error estimates
  • A_STP.???.fits Combined STAMP images for PA???
  • A_udf_f606w_cat???.cat10 Object catalog (direct image) for PA???
    where ??? should be substituted by 117, 126, 134, 217, and 231.

    In addition, combined spectra which where obtained by combining all of the GRAPES spectra obtained at the 5 GRAPES PAs are available. The combination was performed as a simple averaging operation after resampling the spectra onto a common wavelength grid. Portions of spectra which were contaminated above the 25% (see Data Paper for a description) were not used unless absolutely necessary. The Poisson errors were propagated and the standard deviation of the mean between the 5 individual PAs was computed. The larger of either the Poisson noise or the standard deviation of the mean is reported in the combined SPC files.

  • A_SPC.PALL.??.fits Combined, 5 PAs, spectra
  • A_SPC.PALL.??.cn.fits Combined, 5 PAs, spectra with recomputed error estimates
  • A_STP.PALL.??.fits Combined, 5 PAs, STANP images
  • A_obj.PALL.??.cat 5 PAs object catalog corresponding to the content of A_*.fits here ?? is either 14 or 15 (wide and narrow extraction cases).

    All of the FITS files contain N extensions, each contaning a binary FITS tables containing the spectrum of an objects. Each extension was given a name (by which it can be accessed directly) which is derived from the UDF catalog ID of the object. i.e. UDF object number 2225 is contained in the FITS extension names BEAM_2225A . All IDs refer to the v.1.0 UDF released catalog object IDs. A simple text dump of the extension of the spectrum can be obtained using the IRAF task tprint:

    tprint A_SPC.PALL.15.cn.fits[BEAM_2225A]

    The various columns and file format of these files are described in greater details in the aXe user manual (http://www.stecf.org/software/aXe/). Note that in the files A*c*.fits, the CONTAM column was modified from what is described in the aXe Manual. This column now contain the % of the flux in that bin which is estimated to be from another source. We have in the past used a threshold of 25% (CONTAM <25) to consider an object to be essentially uncontaminated.

    What should you get?

    If you want extracted spectra with a slightly higher S/N, at the expense of flux conservation, get the files in the 15th extraction directory.

    If you want the spectra of objects obtained at each of the 5 PAs, to examine, or combined together yourself, get the files A_SPC.???.cn.fits and A_STP.???.fits

    If you want combined spectra of objects obtained by combining the 5 GRAPES epochs, get the files A_SPC.PALL.??.cn.fits

    Get the data

    Just browse the following two directories:
  • Wider extraction: ./14th
  • View the WWW pages for the 14th extraction: Sorted by magnitude, or Sorted by object number
  • Narrower extraction: ./15th
  • View the WWW pages for the 15th extraction: Sorted by magnitude, or Sorted by object number (Single spectrum per page version here)