... or the XDF, for short.
the deepest ever view of the universe, with about 5500 galaxies. this is a two million second exposure!
NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team
more info at spacetelescope.org