Understanding diffuse Galactic radio emission is interesting both in its own right and for minimizing foreground contamination of cosmological measurements. cosmic microwave background experiments have focused on frequencies 10 GHz, whereas 21-cm tomography of the high-redshift universe will mainly focus on 0.2 GHz, for which less is currently known about Galactic emission. Motivated by this, we present a global sky model derived from all publicly available total power large-area radio surveys, digitized with optical character recognition when necessary and compiled into a uniform format, as well as the new Villa Elisa data extending the 1.42-GHz map to the entire sky. We quantify statistical and systematic uncertainties in these surveys by comparing them with various global multifrequency model fits. We find that a principal component based model with only three components can fit the 11 most accurate data sets (at 10, 22, 45 and 408 MHz and 1.42, 2.326, 23, 33, 41, 61, 94 GHz) to an accuracy around 1-10 per cent depending on frequency and sky region. Both our data compilation and our software returning a predicted all-sky map at any frequency from 10 MHz to 100 GHz are publicly available at http://space.mit.edu/home/angelica/gsm.

Abstract. We have analysed the angular power spectra of the Parkes radio continuum and polarisation survey of the Southern galactic plane at 2.4 GHz. We have found that in the multipole range l = 40−250 the angular power spectrum of the polarised intensity is well described by a power-law spectrum with fitted spectral index αL = 2.37 ± 0.21. In the same multipole range the angular power spectra of the E and B components of the polarised signal are significantly flatter, with fitted spectral indices respectively of αE = 1.57 ± 0.12 and αB = 1.45 ± 0.12. Temperature fluctuations in the E and B components are mostly determined by variations in polarisation angle. We have combined these results with other data from available radio surveys in order to produce a full-sky toy model of Galactic synchrotron intensity and linear polarisation at high frequencies (ν > ∼ 10 GHz). This can be used to study the feasibility of measuring the Cosmic Microwave Background polarisation with forthcoming experiments and satellite missions.

We have made scanning observations with the HartRAO 26‐m radio telescope to obtain a pencil‐beam map of 67 per cent of the sky at 2326 MHz. This is the highest resolution and highest frequency radio continuum map of this type made of such a large area of sky.  In this paper we describe the observations and data reduction procedures used to produce the survey. The resulting map has an angular resolution (HPBW) of 20 arcmin, and the rms pointing accuracy is 1.2 arcmin. The rms noise fluctuations are less than 30‐mK TFB over the whole map. We estimate that the uncertainty in the temperature scale is less than 5 per cent, and that the error in the absolute zero level is better than 80‐mK TFB in any direction.  High‐contrast half‐tone images of the data with a model of the diffuse galactic background subtracted are presented. These images show many complex emission structures up to and beyond 50° latitude, and illustrate the quality of the data. Extracts from the survey data are available via FTP by arrangement with the authors.

We present an improved Global Sky Model (GSM) of diffuse Galactic radio emission from 10 MHz to 5 THz, whose uses include foreground modeling for CMB and 21 cm cosmology. Our model improves on past work both algorithmically and by adding new data sets such as the Planck maps and the enhanced Haslam map. Our method generalises the Principal Component Analysis approach to handle non-overlapping regions, enabling the inclusion of 29 sky maps with no region of the sky common to all. We also perform a blind separation of our GSM into physical components with a method that makes no assumptions about physical emission mechanisms (synchrotron, freefree, dust, etc). Remarkably, this blind method automatically finds five components that have previously only been found "by hand", which we identify with synchrotron, free-free, cold dust, warm dust, and the CMB anisotropy. Computing the cross-power spectrum between these blindly extracted components and Planck component maps, we find a strong correlation at all angular scales. The improved GSM is available online at

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