  CW photoinjectors operating at high accelerating gradients promise to
revolutionize many areas of science and applications. They can establish the
basis for a new generation of monochromatic X-ray free electron lasers, high
brightness hadron beams, or a new generation of microchip production. In this
letter we report on the record-performing superconducting RF electron gun with
$\textrm{CsK}_{2}\textrm{Sb}$ photocathode. The gun is generating high charge
electron bunches (up to 10 nC/bunch) and low transverse emittances, while
operating for months with a single photocathode. This achievement opens a new
era in generating high-power beams with a very high average brightness.
