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

The Spitzer Spectroscopic Data Fusion merges miscellaneous spectroscopic information available within "popular" extragalactic survey fields.

Last Updated on 31 August 2026 - https://doi.org/10.5281/zenodo.6368347 - https://www.mattiavaccari.net/df/specz

Vaccari 2026 - https://scixplorer.org/abs/2026RNAAS..10..118V/abstract

Based on the Spitzer Data Fusion Project - https://doi.org/10.5281/zenodo.6120913 - https://www.mattiavaccari.net/df

Vaccari 2026 - https://scixplorer.org/abs/2026RNAAS..10..276V/abstract

Vaccari 2015 - https://scixplorer.org/abs/2015fers.confE..27V/abstract

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 assumed order of decreasing reliability
indicated below for each field.  Since the 31 August 2026 release this order is no longer
arbitrary: large, homogeneous, high-resolution surveys come first, heterogeneous compilations
last, and NED is always the LAST catalogue in every field so that it contributes its unique
redshifts without ever overriding a dedicated survey. If CAT1,...,CATN spec-z catalogs are
available in a given field, Z_1 from CAT1 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. However, Z_1,...,Z_N are included to allow user
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 N catalogues will have ZWHERE=2^0+...+2^(N-1).