Finding the First Stars: The Hamburg/ESO Objective Prism Survey

The Hamburg/ESO survey (HES; [4]) is an objective-prism survey for bright quasars based on IIIa-J plates taken with the ESO Schmidt telescope and its 4◦ prism. It covers the total southern extragalactic sky (δ <+2◦. 5; |b| & 30◦). All 380 Schmidt plates (effective area ∼ 7 000 square degrees) have been taken, and have been digitized and reduced in Hamburg. The spectral range of the HES plates is 3200 Å < λ < 5300 Å, with a seeing-limited spectral resolution of 15 Å at Hγ. This makes it possible to efficiently exploit the stellar content of the survey. Among other interesting objects (e.g. white dwarfs, carbon stars, and field horizontal branch A-type stars; [2]), extremely metal-poor stars can be selected by automated procedures in the digital database of the HES. With its magnitude range of 12 & BJ & 17.5, the HES is more than one magnitude deeper than the HK survey of Beers et al. [1]. Moreover, it covers regions in the sky that are not covered by the HK survey. In result, the HES can increase the total survey volume for metal-poor stars by more than a factor of 4 compared to the HK survey alone.