Large Scale Structure in the Local Universe: The 2MASS Galaxy Catalog

Using twin ground-based telescopes, the Two Micron All Sky Survey (2MASS) scanned both equatorial hemi- spheres, detecting more than 500 million stars and resolving more than 1.5 million galaxies in the near-infrared (1 - 2.2 microns) bands. The Extended Source “Galaxy” Catalog (XSC) embodies both photometric and astrometric whole sky uniformity, revealing large scale structures in the local Universe and extending our view into the Milky Way’s dust-obscured “Zone of Avoidance.” The XSC represents a uniquely unbiased sample of “normal” galaxies, particularly sensitive to the underlying, dominant, stellar mass component of galaxies. The basic properties of the XSC, including photometric sensitivity, source counts, and spatial distribution are presented here. We illustrate the spatial clustering properties, ranging from interacting galaxies to groups and clusters, and finally to the largest “cosmic web” of superclusters spanning the sky.