The ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) I.
  Newly identified X-ray luminous clusters at z>=0.2
  We report 19 intermediate redshift clusters newly detected in the ROSAT
All-Sky survey that are spectroscopically confirmed. They form a part of 911
objects in the REFLEX II cluster catalogue with a limiting flux of
1.8\times10^12 erg/s/cm2 in the 0.1-2.4 keV ROSAT band at redshift z >= 0.2. In
addition we report three clusters from the REFLEX III supplementary catalogue,
which contains objects below the REFLEX II flux limit but satisfies the
redshift constraint above. These clusters are spectroscopically followed-up by
our ESO NTT-EFOSC2 campaigns for the redshift measurement. We describe our
observing and data reduction methods. We show how X-ray properties such as
spectral hardness ratio and source extent can be used as important diagnostics
in selecting galaxy cluster candidates. Physical properties of the clusters are
subsequently calculated from the X-ray observations. This sample contains the
high mass and intermediate-redshift galaxy clusters for astrophysical and
cosmological applications.
