eeHIFLUGCS\: Cosmology with virgul400 Galaxy Clusters

We propose to complete the last 10% of highquality observations for theeeHIFLUGCS galaxy cluster sample (31 of 376 clusters). The sample is based onROSAT with completely and homogeneously redetermined fluxes as well as updatedredshifts. For the already observed clusters we have also identified >10double/triple clusters and clusters dominated by AGN emission, which then fallbelow the flux limit of 5e 12 erg/s/cm2. With the completed followupobservations we will decrease the uncertainties in OmegaM by a factor of 2.8compared to those obtained with the HIFLUGCS sample. If these 10% do not getobserved, the fluxlimited sample drops by almost a factor of 3 to adisappointing 137 clusters. The observations will have long lasting legacy value for a range of astrophysical studies truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]