We present new full-sky temperature and polarization maps in five frequency bands from 23 to 94 GHz , based on data from the first five years of the WMAP sky survey .
The new maps are consistent with previous maps and are more sensitive .
The five-year maps incorporate several improvements in data processing made possible by the additional years of data and by a more complete analysis of the instrument calibration and in-flight beam response .
We present several new tests for systematic errors in the polarization data and conclude that W band polarization data is not yet suitable for cosmological studies , but we suggest directions for further study .
We do find that Ka band data is suitable for use ; in conjunction with the additional years of data , the addition of Ka band to the previously used Q and V band channels significantly reduces the uncertainty in the optical depth parameter , \tau .
Further scientific results from the five year data analysis are presented in six companion papers and are summarized in § 7 of this paper .

With the 5 year WMAP data , we detect no convincing deviations from the minimal 6-parameter \Lambda CDM model : a flat universe dominated by a cosmological constant , with adiabatic and nearly scale-invariant Gaussian fluctuations .
Using WMAP data combined with measurements of Type Ia supernovae ( SN ) and Baryon Acoustic Oscillations ( BAO ) in the galaxy distribution , we find ( 68 % CL uncertainties ) : \Omega _ { b } h ^ { 2 } = 0.02267 ^ { +0.00058 } _ { -0.00059 } , \Omega _ { c } h ^ { 2 } = 0.1131 \pm 0.0034 , \Omega _ { \Lambda } = 0.726 \pm 0.015 , n _ { s } = 0.960 \pm 0.013 , \tau = 0.084 \pm 0.016 , and \Delta _ { \cal R } ^ { 2 } = ( 2.445 \pm 0.096 ) \times 10 ^ { -9 } at k = 0.002 ~ { } { Mpc ^ { -1 } } .
From these we derive : \sigma _ { 8 } = 0.812 \pm 0.026 , H _ { 0 } = 70.5 \pm 1.3 { km~ { } s ^ { -1 } ~ { } Mpc ^ { -1 } } , \Omega _ { b } = 0.0456 \pm 0.0015 , \Omega _ { c } = 0.228 \pm 0.013 , \Omega _ { m } h ^ { 2 } = 0.1358 ^ { +0.0037 } _ { -0.0036 } , z _ { reion } = 10.9 \pm 1.4 , and t _ { 0 } = 13.72 \pm 0.12 \mbox { Gyr } .
The new limit on the tensor-to-scalar ratio is r < 0.22 \mbox { ( 95 \% CL ) } , while the evidence for a running spectral index is insignificant , dn _ { s } / d \ln { k } = -0.028 \pm 0.020 ( 68 % CL ) .
We obtain tight , simultaneous limits on the ( constant ) dark energy equation of state and the spatial curvature of the universe : -0.14 < 1 + w < 0.12 \mbox { ( 95 \% CL ) } and -0.0179 < \Omega _ { k } < 0.0081 \mbox { ( 95 \% CL ) } .
The number of relativistic degrees of freedom , expressed in units of the effective number of neutrino species , is found to be N _ { eff } = 4.4 \pm 1.5 ( 68 % CL ) , consistent with the standard value of 3.04 .
Models with N _ { eff } = 0 are disfavored at > 99.5 % confidence .
Finally , new limits on physically motivated primordial non-Gaussianity parameters are -9 < f _ { NL } ^ { local } < 111 ( 95 % CL ) and -151 < f _ { NL } ^ { equil } < 253 ( 95 % CL ) for the local and equilateral models , respectively .