The Spitzer Spectroscopic Data Fusion - Merged Spectroscopic Redshift Catalogs in Spitzer Fields

Merged Spec-Z ("specz-merged") catalogs merge miscellaneous spec-z information available
within a given field. Different spec-z catalogs available within a given field are merged
(using a search radius of 1.0 arcsec), and for sources with multiple spec-z measurements
the most reliable one is chosen following the (largely arbitrarily) assumed order of decreasing
reliability indicated below for each field. If CAT1,...,CATN spec-z catalogs are available
in a given field, Z_1 from CAT1 (i.e. NED) is adopted as "best" redshift (i.e. ZBEST),
if available, otherwise Z_2 from CAT_2 is adopted if available, and so on up to Z_N and CAT_N.
In using ZBEST it's thus important to bear in mind that this is not necessarily actually the
"best" redshift for science purposes, and in particular that the choice of NED as CAT1 is often
not ideal. However, Z_1,...,Z_N are included to allow users to define the "best" redshift based
on their science needs when multiple redshift estimates are available for a given source.
ZFLAG specifies which catalog is providing the ZBEST value according to the CATN number below.
ZCLASS is meant to provide further info about the class/quality of the spectroscopic redshift
measurement, but for the time being is not populated and is simply a copy of ZFLAG.
ZWHERE is an additional binary/bit flag indicating in which of the N catalogs each source
was given a spec-z estimate in. ZWHERE will e.g. be 2^0=1 if a redshift if available *only*
from CAT_1, whereas it will be 2^0+2^1=3 if a redshift is available *only* from CAT1 and CAT2,
so that a source with a redshift available from all catalogues will have ZWHERE=2^0+...+2^n.

See AAAREADME.SPECZ-MERGED and https://adsabs.harvard.edu/abs/2015fers.confE..27V

See also https://www.mattiavaccari.net/df and https://www.mattiavaccari.net/df/specz