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The distances to 50 galaxies in the vicinity of three most nearby galaxy clusters were measured. The radius of the "zero velocity sphere", isolating each group from the cosmological expansion is in the range from 0.95 to 1.25 Mpc for these groups, leads to the estimates of the total mass of groups ranging from 1.2 to 2.7 trillion solar masses. These results agree with the value of the mean matter density in the Local Universe from 0.05 to 0.10 in critical density units. The velocities of random motions of the group centroids relative to the Hubble expansion do not exceed 35 km/s at the Hubble constant of 70km/s/Mpc, giving independent evidence of low matter density in the Local Universe.
Based on the energy distribution in the spectra obtained from the BTA observations, parent galaxies of gamma-ray bursts do not differ from normal "field" galaxies with the same magnitudes and redshifts, which allows to determine the average annual rate of gamma-ray bursts directly from observations.
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