What can cosmic microwave background observations already say about cosmological parameters in open and critical-density cold dark matter models?

We use a combination of the most recent cosmic microwave background (CMB) flat-band power measurements to place constraints on Hubble's constant h and the total density of the universe Omega(0) in the context of inflation-based cold dark matter (CDM) models with no cosmological constant. We use Chi(2) minimization to explore the four-dimensional parameter space having as free parameters, h, Omega(0), the power-spectrum slope n, and the power-spectrum normalization at l = 10. Conditioning on Omega(0) = 1, we obtain h = 0.33 +/- 0.08. Allowing no to be a free parameter reduces the ability of the CMB data to constrain h, and we obtain 0.26 < h < 0.97 with a best-fit value at h = 0.40. We obtain Omega(0) = 0.85 and set a lower limit Omega(0) > 0.53. A strong correlation between acceptable h and Omega(0) values leads to a new constraint Omega(0)h(1/2) = 0.55 +/- 0.10. We quote Delta chi(2) = 1 contours as error bars; however, because of nonlinearities of the models, these may be only crude approximations to 1 a confidence limits. A favored open model with Omega(0) = 0.3 and h = 0.70 is more than similar to 4 sigma from the CMB data best-fit model and is rejected by goodness-of-fit statistics at the 99% confidence level. High baryonic models (Omega(b)h(2) similar to 0.026) yield the best CMB chi(2) fits and are more consistent with other cosmological constraints. The best-fit model has n = 0.91(-0.09)(+0.29) and Q(10) = 18.01(-1.5)(+1.2) mu K. Conditioning on n = 1, we obtain h = 0.55(-0.19)(+0.13), Omega(0) = 0.70 with a lower limit Omega(0) > 0.58, and Q(10) = 18.0(-1.5)(+1.4) mu K. The amplitude and position the dominant peak in the best-fit power spectrum are A(peak) = 76(-7)(+3) mu K and l(peak) = 260(-20)(+30). Unlike the Omega(0) = 1 case we considered previously, CMB h results are now consistent with the higher values favored by local measurements of h but only if 0.55 less than or similar to Omega(0) 0.85. Using an approximate joint likelihood to combine our CMB constraint on Omega(0)h(1/2) with other cosmological constraints, we obtain h = 0.58 +/- 0.11 and Omega(0) = 0.65(-0.15)(+0.16).