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 availablewithin 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 measurementsthe most reliable one is chosen following the assumed order of decreasing reliabilityindicated below for each field. Since the 31 August 2026 release this order is no longerarbitrary: large, homogeneous, high-resolution surveys come first, heterogeneous compilationslast, and NED is always the LAST catalogue in every field so that it contributes its uniqueredshifts without ever overriding a dedicated survey. If CAT1,...,CATN spec-z catalogs areavailable 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 / actuallyTHE "best" redshift for science purposes. However, Z_1,...,Z_N are included to allow userto define the "best" redshift based on their science needs when multiple redshift estimatesare 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 redshiftmeasurement, 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 sourcewas 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).