The TopHat Cosmic Microwave Background anisotropy experiments

We have developed a program of complementary balloon-borne experiments to measure the Cosmic Microwave Background Radiation anisotropy on angular scales from similar to 50 degrees down to similar to 20'. The instruments observe at frequencies between 150 and 690 GHz and one of them will be flown on an Antarctic circumpolar long duration flight. With high sensitivity, large sky coverage, and well-characterized systematic errors, the results of this program can be used to strongly constrain cosmological models and probe the early stages of large-scale structure formation in the Universe.