Annu. Rev. Astron. Astrophys. 1992. 30: 653-703 Copyright © 1993 by Annual Reviews. All rights reserved

3.2.6 SUMMARY OF UPPER LIMITS IN THE RANGE 0.1-100' The lowest upper limits over the range of arc seconds to one degree are provided by the VLA observations of Fomalont et al (1988) and Partridge (private communication), by the OVRO observations of Readhead et al (1989) and by the South Pole results of Meinhold and Lubin (1991). On these scales the cold dark matter models predict a quasi-Gaussian spectrum for the angular distribution in the sky fluctuations, so that these results may be compared using the Gaussian approximation to the distribution of fluctuations. We have therefore analyzed the results of these four experiments (Myers et al 1992) for the case of a Gaussian distribution with the results shown in Figure 2. It can be seen that, on this assumed distribution spectrum, the 95% confidence upper limits on T/T over the range 0.3-100' are < 4 x 10^-5, and over much of this range the limits are < 3 x 10^-5.

Figure 2. Upper limits on the anisotropy of the microwave background radiation on angular scales 0'.1-100'. The curves show the 95% confidence limits that would be placed on the amplitude of the anisotropy in models with Gaussian W(k) - a reasonable approximation to the background fluctuations produced in many models, but a bad approximation in some (eg. string) models. Upper dashed curve - Fomalont et al (1988), VLA 4.9 GHz, 60" resolution; lower dashed curve - Partridge (private communication), VLA 8 GHz, estimate based on preliminary analysis; upper solid curve - Myers et al (1992), 20 GHz, OVRO ``RING'' program; lower solid curve - Readhead et al (1989), 20 GHz, OVRO ``NCP'' program; upper dotted curve - Meinhold & Lubin (1991) 91 GHz ``South Pole'' observations, calculated from Equation 4 of Vittorio et al (1991); lower dotted curve - Meinhold & Lubin + Readhead et al (1989) combined results.