The Tenerife cosmic microwave background maps: Observations and first analysis

The results of the Tenerife cosmic microwave background (CMB) experiments a re presented. These observations cover 5000 and 6500 deg(2) on the sky at 1 0 and 15 GHz, respectively, centered on decl. similar to +35 degrees. The e xperiments are sensitive to multipoles l = 10-30 that correspond to the Sac hs-Wolfe plateau of the CMB power spectra. The sensitivity values of the da ta are similar to 31 and similar to 12 mu K at 10 and 15 GHz, respectively, in a beam-size region (5 degrees x 5 degrees). The data at 15 GHz show cle ar detection of structure at high Galactic latitude; the results at 10 GHz are compatible with these, but at lower significance. A likelihood analysis of the 10 and 15 GHz data at high Galactic latitude, assuming a flat CMB b and power spectrum, gives a signal Delta T-l = 30(-8)(+10) mu K (68% C.L.). Including the possible contaminating effect due to the diffuse Galactic co mponent, the CMB signal is Delta T-l = 30(-11)(+15) mu K. These values are stable against the Galactic cut chosen. Assuming a Harrison-Zeldovich spect rum for the primordial fluctuations, the above values imply an expected qua drupole Q(rms-ps) = 20(-7)(+10) mu K, which agrees with previous results fr om these experiments, and which are compatible with the COBE DMR data in th e case of the standard inflationary cold dark matter models.