Curvature-cosmology is a tired-light cosmology that predicts a well-defined static and stable universe. Since it is a complete challenge to the big bang paradigm, it can only be judged by its agreement with direct cosmological observations. It predicts a universe of a hydrogen plasma with a temperature of $2.456times10^9,$K [observed: $2.62times 10^9$K] and a cosmic background radiation temperature of 2.736 K [observed: 2.725K]. It has only one parameter which is the density of the cosmic plasma. In addition this paper provides a new simpler raw data analysis for Type Ia supernova which provides excellent predictions for the redshift variation of Type I supernova light curve width and magnitude. A new discovery is intrinsic magnitude distribution. The analysis of 746,922 quasars provides important cosmological information on the distribution on intrinsic magnitudes and the density distribution of quasars. Other major observations that are shown to be consistent with Curvature-cosmology are: Tolman surface density, galaxy clusters, angular size, galaxy distributions, X-ray background radiation, and quasar variability. It does not need inflation, dark matter or dark energy.