  We have detected statistically significant correlations between the cosmic
microwave background and two tracers of large-scale structure, the HEAO1 A2
full sky hard X-ray map and the NVSS 1.4 GHz, nearly full sky radio galaxy
survey. The level of correlations in these maps is consistent with that
predicted for the integrated Sachs-Wolfe (ISW) effect in the context of a
Lambda CDM cosmological model and, therefore, provides independent evidence for
a cosmological constant. A maximum likelihood fit to the amplitude of the ISW
effect relative to the predicted value is 1.13 +- 0.35 (statistical error
only).
