DEEP KECK u-BAND IMAGING OF THE HUBBLE ULTRA DEEP FIELD: A CATALOG OF z ∼ 3 LYMAN BREAK GALAXIES

We present a sample of 407 z similar to 3 Lyman break galaxies (LBGs) to a limiting isophotal u-band magnitude of 27.6 mag in the Hubble Ultra Deep Field. The LBGs are selected using a combination of photometric redshifts and the u-band drop-out technique enabled by the introduction of an extremely deep u-band image obtained with the Keck I telescope and the blue channel of the Low Resolution Imaging Spectrometer. The Keck u-band image, totaling 9 hr of integration time, has a 1 sigma depth of 30.7 mag arcsec(-2), making it one of the most sensitive u-band images ever obtained. The u-band image also substantially improves the accuracy of photometric redshift measurements of similar to 50% of the z similar to 3 LBGs, significantly reducing the traditional degeneracy of colors between z similar to 3 and z similar to 0.2 galaxies. This sample provides the most sensitive, high-resolution multi-filter imaging of reliably identified z similar to 3 LBGs for morphological studies of galaxy formation and evolution and the star formation efficiency of gas at high redshift.