QUIJOTE scientific results - IV. A northern sky survey in intensity and polarization at 10-20 GHz with the multifrequency instrument

We present QUIJOTE intensity and polarization maps in four frequency bands centred around 11, 13, 17, and 19 GHz, and covering approximately 29 000 deg(2), including most of the northern sky region. These maps result from 9000 h of observations taken between May 2013 and June 2018 with the first QUIJOTE multifrequency instrument (MFI), and have angular resolutions of around 1 degrees, and sensitivities in polarization within the range 35-40 mu K per 1 degrees beam, being a factor similar to 2-4 worse in intensity. We discuss the data processing pipeline employed, and the basic characteristics of the maps in terms of real space statistics and angular power spectra. A number of validation tests have been applied to characterize the accuracy of the calibration and the residual level of systematic effects, finding a conservative overall calibration uncertainty of 5 per cent. We also discuss flux densities for four bright celestial sources (Tau A, Cas A, Cyg A, and 3C274), which are often used as calibrators at microwave frequencies. The polarization signal in our maps is dominated by synchrotron emission. The distribution of spectral index values between the 11 GHz and WMAP 23 GHz map peaks at beta = -3.09 with a standard deviation of 0.14. The measured BB/EE ratio at scales of l = 80 is 0.26 +/- 0.07 for a Galactic cut |b| > 10 degrees. We find a positive TE correlation for 11 GHz at large angular scales (l less than or similar to 50), while the EB and TB signals are consistent with zero in the multipole range 30 less than or similar to l less than or similar to 150. The maps discussed in this paper are publicly available.

Automated summary

We present intensity and polarization maps at four frequency bands centred around 11, 13, 17, and 19 GHz, covering a large portion of the northern sky region. The maps were derived from observations made between May 2013 and June 2018 using the first QUIJOTE multifrequency instrument (MFI), with high angular resolutions and sensitivities. We discuss the data processing pipeline, calibration accuracy, and characteristics of the maps.