For the operation of free electron lasers (FELs) like the Eu-
ropean XFEL and FLASH located at DESY, Hamburg Site,
high quality electron beams are required already from the
source. The Photo Injector Test facility at DESY, Zeuthen
Site (PITZ), was established to develop, characterize and
optimize electron sources for such FELs. Last year the work
at PITZ focused on the optimization of a photo injector op-
erated very close to the startup parameters of the European
XFEL. This implies photocathode laser pulses with a Gaus-
sian temporal profile of about 11 − 12 ps FWHM to drive
the photo gun operated at a gradient of about 53MV/m.
Significant effort was spent on the electron beam character-
ization and optimization for various bunch charges. Emit-
tance measurements were performed as a function of major
accelerator parameters such as main solenoid current, laser
spot size on the cathode and the gun launching phase. The
requirement on the beam emittance for a bunch charge of
500 pC for the European XFEL commissioning phase has
been demonstrated. Results of these studies accompanied
with the corresponding simulations are presented in this
paper.