THE TENERIFE OBSERVATIONS .1. THE PERFORMANCE OF THE TENERIFE CMB EXPERIMENTS

Beamswitching radiometers operating at the Teide Observatory, Tenerife , have detected structure in the cosmic microwave background (CMB). Th e observations have been made at frequencies of 10.45, 14.9 and 33 GHz using in each case 5 degrees beamwidths switched +/- 8 degrees. At ea ch frequency, independent data streams reveal the same structure in th e microwave sky at high galactic latitudes. The main features are seen in the scans at all 3 frequencies. The 14.9 and 33 GHz scans appear t o be largely free of Galactic and radio source contributions. When the 14.9 and the 33 GHz data are added they show a hot spot at Dec = 40 d egrees, RA = 185 degrees which is 6 times the rms noise in the beam. A ll the evidence indicates that this is structure in the CMB. Interfero meters are being operated or commissioned to extend the survey for CMB structure to smaller angular scales (1 degrees to 3 degrees). Prelimi nary results are given for a high sensitivity interferometer survey at 5 GHz.