BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B -mode polarization of the Cosmic Microwave Background ( CMB ) at degree angular scales .
We present results from an analysis of the data acquired during three seasons of observations at the South Pole ( 2006 to 2008 ) .
This work extends the two-year result published in , with additional data from the third season and relaxed detector-selection criteria .
This analysis also introduces a more comprehensive estimation of band-power window functions , improved likelihood estimation methods and a new technique for deprojecting monopole temperature-to-polarization leakage which reduces this class of systematic uncertainty to a negligible level .
We present maps of temperature , E - and B -mode polarization , and their associated angular power spectra .
The improvement in the map noise level and polarization spectra error bars are consistent with the 52 % increase in integration time relative to .
We confirm both self-consistency of the polarization data and consistency with the two-year results .
We measure the angular power spectra at 21 \leq \ell \leq 335 and find that the EE spectrum is consistent with Lambda Cold Dark Matter ( \Lambda CDM ) cosmology , with the first acoustic peak of the EE spectrum now detected at 15 \sigma .
The BB spectrum remains consistent with zero .
From B -modes only , we constrain the tensor-to-scalar ratio to r = 0.03 ^ { +0.27 } _ { -0.23 } , or r < 0.70 at 95 % confidence level .