letter_catalog

This file has an entry for every object selected to pass a particular set of "pre-redshift" cuts on the VAGC data (as described on the LSS page. It contains information on the classification of that object, its location in the window, its magnitude, and the flux limit at that object.

The columns are:

1. OBJECT_POSITION: index in the VAGC catalog (zero-indexed)
2. RA: Right ascension, J2000, degrees
3. DEC: Declination, J2000, degrees
4. M: Apparent magnitude, extinction corrected (in the band specified for this pre-redshift subsample)
5. MMAX: Apparent magnitude faint limit for this object
6. ILSS: index in the lss_geometry file of the polygon containing this object
7. IWINDOW: index in the window file for this subsample of the polygon containing this object
8. LETTER_MASK: bitmask specifying what happened to this object:
   • 0 (LETTER_TARGET): it is a target passing our cuts in the photometric catalog
   • 1 (LETTER_TILED_TARGET): it was a tiled target in the target reductions
   • 2 (LETTER_TILED): it was assigned a fiber on a tile
   • 3 (LETTER_TRIED): a spectrum was attempted, or a redshift was gotten by fixing a collision
   • 4 (LETTER_GOT): a redshift was determined (by a spectrum or fixing of collisions)
   • 5 (LETTER_FIXED): the redshift was gotten by fixing a collision
   • 6 (GALAXY): it was classified as a galaxy

NYU Value-Added Galaxy Catalog

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