lss_index
This file contains an entry for every galaxy in the VAGC, with its
position, its geometrical information, and why it was selected in the
VAGC. It is useful because it connects the VACG catalog to the
geometrical information the
lss_geometry and lss_bsmask
files.
It exists at
$LSS_REDUX/sample/lss_index.sample.fits
It contains the columns:
- RA: Right ascension, J2000, degrees
- DEC: Declination, J2000, degrees
- Z: redshift (-1 if not available)
- ZTYPE: source of the redshift value (0: no redshift, 1:
SDSS, 2: 2dFGRS, 3: PSCz, 4: RC3)
- SECTOR: sector number in the tiling geometry (each sector
is an area covered by a unique set of tiles)
- FGOTMAIN: fraction of targets in Main which succcessfully
get redshifts in this sector
- M: apparent magnitude (extinction-corrected r-band
Petrosian)
- MMAX: effective Main sample flux limit
- ICOMB: Index in the
lss_combmask file (-1 if it outside the window OR inside the
bright star mask)
- ILSS: Index in the
lss_geometry file (-1 if it is outside the window OR inside the
bright star mask)
- VAGC_SELECT: Bit mask indicating nature of the selection
(see the description for the object_sdss_imaging file).
As an example of how you would use this, you might want to select
tiled targets which are in the large-scale structure area. Then you
would apply the criteria:
(ILSS!=-1) && (VAGC_SELECT&1)
The objects that survived would be your sample, limited to the LSS
area, and you could then look at the corresponding values in the object_sdss_tiling, object_sdss_spectro, and object_sdss_imaging files to
look at the properties of this object.
NYU Value-Added Galaxy Catalog