In addition to the primary SDSS photometry and spectroscopy, there are a few extra catalogs created by our collaborators that are distributed through the SAS. These Value-Added Catalogs (VACs) are listed below, and include catalogs that were released in earlier data releases.
WISE Forced Photometry
Catalog of SDSS and WISE sources, matched using forced photometry.
This catalog contains “forced photometry” matching between SDSS sources and sources from the Wide-Field Infrared Survey Explorer (WISE; Wright et al. 2010). The WISE forced photometry assumes that all objects detected and measured by SDSS appear in the WISE images with the same morphologies, and then asks how bright those objects should be to best match the WISE data. This is useful because it allows us to extract information from the WISE images using knowledge of the existence and shapes of objects from the higher-resolution SDSS imaging. There is no need for catalog matching, and all sources get a flux measurement, even if the flux is below a formal detection limit (although low-significance flux measurements will understandably still be noisy). This allows, for example, making statistical measures of the WISE flux of classes of SDSS objects (so-called, stacking analyses). The catalog is described in detail in Lang, Hogg, & Schlegel 2016.
Catalog last modified: 2021-12-06 07:36:54