STUDIES OF COSMIC MICROWAVE BACKGROUND STRUCTURE AT DEC=-DEGREES .1. THE PERFORMANCE OF THE TENERIFE EXPERIMENTS(40)

The direct identification of structure in the cosmic microwave backgro und (CMB) is a major objective of observational cosmology. We present a detailed discussion of observations of such structure detected on a 5 degrees scale in the CMB using beam-switching radiometers at 10, 15 and 33 GHz sited in Tenerife. This long-term experiment has reached se nsitivities of a few tens of mu K at each frequency and is now able to measure directly features believed to be of intrinsic CMB origin. We describe the critical elements of the system design capable of reachin g these high sensitivities. An evaluation is made of the atmospheric w ater vapour contribution from the available multifrequency observation s. The data taken in the high Galactic latitude part of the Dec. = + 4 0 degrees scan clearly show features which are seen in independent dat a sets at each frequency. Tests are given which demonstrate that these features are of celestial origin. An assessment of the Galactic and e xtragalactic contributions indicates that the 33-GHz results are essen tially unaffected. These observations represent the first direct detec tion of individual hot and cold features in the intrinsic CMB arising from the initial singularity.