What does the GALEX data pipeline do?
A detailed discussion may be found in the GALEX Pipeline Data Guide, but in short, the pipeline converts GALEX photon lists, satellite telemetry data and any necessary corollary data into calibrated images and catalogs. The GALEX Science Operations Center (SOC) receives data from the satellite and unpacks it into time-tagged photon lists, instrument/SC housekeeping and satellite aspect information, and uses it to generate images, spectra and source catalogs. An astrometric module corrects the photon positions for detector and optical distortions and determines an aspect solution using star positions from the time-tagged photon data, a photometric module accumulates the photons into count and intensity maps and extracts sources from images, and (for grism observations) a spectroscopic module uses image source catalog inputs to extract spectra of individual sources from the multiple slitless grism images.
