086405

We propose to complete the last 10% of high-quality observations for the eeHIFLUGCS galaxy cluster sample openPar36 of 376 clustersclosePar. The sample is based on ROSAT with completely and homogeneously redetermined fluxes as well as updated redshifts. For the already observed clusters we have also identified >10 double-triple clusters and clusters dominated by AGN emission comma which then fall below the flux limit of 5e- 12 erg-s-cm2. With the completed follow-up observations we will decrease the uncertainties in OmegaM by a factor of 2.8 compared to those obtained with the HIFLUGCS sample. If these 10% do not get observed comma the flux-limited sample drops by almost a factor of 3 to a disappointing 137 clusters. The observations will also have long lasting legacy value for a range of astrophysical studies