SWIRE MIPS 70/160 Data Catalog Definition

SWIRE Overview

The Spitzer Wide-area InfraRed Extragalactic survey (SWIRE), the largest Spitzer Legacy program, is a wide-area, imaging survey to trace the evolution of dusty, star-forming galaxies, evolved stellar populations, and AGN as a function of environment, from redshifts z~3 to the current epoch. SWIRE surveys 6 high-latitude fields, totaling ~50 sq. deg. in all 7 Spitzer bands: 3.6, 4.5, 5.8, and 8 microns with IRAC and 24, 70, and 160 microns with MIPS (Lonsdale et al. 2003). The SWIRE Legacy Extragalactic Source Catalogs will eventually contain in excess of 2 million IR-selected galaxies, from those dominated by the light of stellar populations detected primarily by IRAC, to starbursts, ultra-luminous infrared galaxies and AGN detected also by MIPS. The SWIRE project page can be found here.

The key scientific goals of SWIRE are to determine: (1) the evolution of actively star-forming and passively evolving galaxies to determine the history of galaxy formation in the context of cosmic structure formation; (2) the evolution of the spatial distribution and clustering of evolved galaxies, starbursts and AGN in the key redshift range, 0.5<z<1.5, when the sharp decline in star formation activity has occurred; (3) the evolutionary relationship between ``normal galaxies'' and AGN, and the contribution of AGN accretion energy vs. stellar nucleosynthesis to the cosmic backgrounds. The large area of SWIRE is important to establish statistically significant population samples over enough volume cells that we can resolve the star formation history as a function of epoch and environment, i.e. in the context of structure formation. The large volume is also optimised for finding rare objects.

SWIRE Fields

The Spitzer Wide-area InfraRed Extragalactic survey (SWIRE; Lonsdale et al. 2003) Versions 2.0 & 3.0 data products releases (Spring 2005 & Fall 2005) include an image atlas and source catalogs for most of the six SWIRE fields to be observed by Spitzer:

The release includes both Spitzer IRAC and MIPS mid/far-infrared data products for all four fields as well as U, g', r', i', and Z optical data covering selected subregions of the data (McMahon et al. 2001, Gonzalez-Solares et al. 2004). The document "The SWIRE Data Release 2: Image Atlases and Source Catalogs for ELAIS-N1, ELAIS-N2, XMM-LSS, and the Lockman Hole" by Surace et al. describes the creation of these data products in detail [ SWIRE Delivery Document (PDF)]. For each of the MIPS bands, the SWIRE team has produced single-band catalogs. Below is a selected subset of the description of the columns found within the single-band MIPS 70 micron and 160 micron catalogs. the MIPS-24 micron catalog column descriptions are available here. The column descriptions for IRAC/Ancillary/Band-merged catalogs can be found here.

SWIRE MIPS-70 and MIPS-160 Catalog Column Descriptions

Gator serves the SWIRE Spring 2005 EN1, EN2, Lockman, and XMM-LSS catalogs, and the Fall 2005 CDFS and ES1 catalogs. The column descriptions for the far-infrared catalogs are listed below.

Column Name Data Type Units Description
  An internal record number from the master database table from which the sources were selected. It is included in the released Catalog for database linkage reasons. It is not useful as a sequential record number because it does not increase monotonically with Right Ascension, and because there are gaps in a sequential listing of CNTR for the catalog. However it is useful as a purely numerical source identifier within the Table.
  The name of the source, conforming to IAU standards. All sources in the 70 and 160 catalogs are labeled "SWIRE", followed an integer denoting the version of the SWIRE Data Products. The MIPS band is next indicated by the string "_70_" or "_160_". The remainder of the name is the J2000 position of the object in hhmmss+ddmmss format. Sufficient precision is provided to ensure the name is unique.
The Right Ascension and Declination of the source in J2000 decimal degrees. The position is determined by the point-source-fitting extraction using the MOPEX software (Makovoz & Marleau 2005, PASP, 117, 1113), and the World Coordinate System keywords in the header of the mosaicked image. For the 160um band only, a correction of about 5 arcseconds has been made in the catalog coordinates, which is uncorrected in the released 160um mosaics.
The uncertainties in the celestial coordinates, in arcseconds, as determined from point-source-fitting and the mosaic uncertainty image. The quantities derive from the square root of the corresponding elements of the covariance matrix. The sign of "unc_rd" is the same as the sign of the covariance between right ascension and declination.
  A detection identification number, retained only for internal traceback purposes.
The point-source-fitted flux density and uncertainty from the MOPEX package. The flux density is quoted for an assumed spectrum varying as the reciprocal of frequency.
The flux density measured in a large aperture (27 arcsecond radius for 70um; 60 arcsecond radius for 160um). This column should only be considered for bright, possibly extended sources. In general, the flux_prf value is more reliable.
  The signal-to-noise ratio as determined from point-source fitting.
  Flag for the extraction based on manual examination of the extractions. A value of 1 means the source is brighter than the nominal 5-sigma flux limit and no problems were noted. A value of 2 indicates the source brightness is below the flux limit and may be unreliable. A value of 3 indicates the source is considered reliable, but the flux may be under- or over-estimated, due either to proximity to the noisy border of the mosaic, or because the source was extracted as two detections by MOPEX.
  The reduced chi-squared value from the point-source fitting. A value near 1 is expected for sources that are fitted well by the point-response function used.