The Galaxy Evolution Explorer (GALEX)

Abstract.

The Galaxy Evolution Explorer (GALEX) is a Space Ultraviolet Imaging and Spectroscopic Survey Small Explorer mission that will map the star formation history of the universe over 0 < z < 2, a key to our understanding of the formation and evolution of galaxies and the origins of stars and heavy elements. It will provide the critical, missing survey of the z=0 UV universe, bridge the gap between the z=0 and redshifted UV universe explored by large optical telescopes, the Hubble Space Telescope and NGST, and provide the framework and targets for numerous high-priority investigations (HST, FUSE, AXAF, and SIRTF). An Associate Investigator Program will provide opportunities to fully exploit the mission and data potential. In addition to an All-Sky survey in two bands (150 and 240 nm), GALEX will perform a deep imaging survey of 160 square degrees to m(AB)=26, and spectroscopic surveys over a range of depths and sky coverages. These regions are being selected in coordination with other ongoing and planned surveys at other wavelengths, including the visible, near and far-IR and X-ray. GALEX uses the space ultraviolet to derive extinction corrected star formation rates. Slitless grism spectroscopy is highly efficient, providing 100,000 galaxy spectra in one year. The 50 cm telescope, operating from 135-300 nm exploits high-resolution, large-format microchannel-plate detectors and optical coatings to attain the deep, broad-band imaging and spectroscopy required.