(Sloan Extension for Galactic Understanding and Exploration)

SEGUE (Sloan Extension for Galactic Understanding and Exploration) will map the structure and stellar makeup of the Milky Way Galaxy.

Although designed as a high-latitude, extragalactic survey, SDSS made numerous discoveries about the Milky Way, revealing new structures in the Galaxy's stellar halo. SEGUE will include 3,500 square degrees of new imaging, some on a regular grid extending through the Galactic Plane — sparsely sampling the whole sky from Apache Point Observatory — and some sampling structures like the Sagittarius Dwarf Tidal Stream.

SEGUE will also obtain spectra of 240,000 stars, with typical radial velocity accuracy of 10 km/s and typical chemical abundance accuracy of 0.3 dex. These data will provide invaluable insights into the structure of the Milky Way, the formation of its main components and the stellar processes that built the elements of the periodic table.

tidal stream color magnitude diagram
A tidal stream of stars surrounding the globular cluster Palomar 5 (left). A color-magnitude diagram of stars along a line of sight through the stellar halo, revealing the stellar populations of several distinct Galactic structures (right).

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