The Tenerife cosmic microwave background maps:: Observations and first analysis

The results of the Tenerife cosmic microwave background (CMB) experiments are presented. These observations cover 5000 and 6500 deg(2) on the sky at 10 and 15 GHz, respectively, centered on decl. similar to +35 degrees. The experiments are sensitive to multipoles l = 10-30 that correspond to the Sachs-Wolfe plateau of the CMB power spectra. The sensitivity values of the data 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 clear 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 band 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 component, 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 spectrum for the primordial fluctuations, the above values imply an expected quadrupole Q(rms-ps) = 20(-7)(+10) mu K, which agrees with previous results from these experiments, and which are compatible with the COBE DMR data in the case of the standard inflationary cold dark matter models.