CMB maps

Overview

This section describes the CMB maps produced from the Planck data. These products are derived from some or all of the nine frequency channel maps using different techniques and, in some cases, using other constraints from external data sets. Here we give a brief description of each product and how it is obtained, followed by a description of the FITS file containing the data and associated information. All the details can be found in Planck-2015-A09 and .

CMB maps

CMB maps have been produced using four different methods: COMMANDER, NILC, SEVEM, and SMICA, as described in the CMB and foreground separation section and also in Appendices A-D of Planck-2015-A09 and references therein.

As discussed extensively in Planck-2015-A01, Planck-2015-A06, Planck-2015-A08, and Planck-2015-A09, the residual systematics in the Planck 2015 polarization maps have been dramatically reduced compared to 2013, by as much as two orders of magnitude on large angular scales. Nevertheless, on angular scales greater than 10 degrees, correponding to l < 20, systematics are still non-negligible compared to the expected cosmological signal.

It was not possible, for this data release, to fully characterize the large-scale residuals from the data or from simulations. Therefore all results published by the Planck Collaboration in 2015 which are based on CMB polarization have used maps which have been high-pass filtered to remove the large angular scales. We warn all users of the CMB polarization maps that they cannot yet be used for cosmological studies at large angular scales.

For convenience, we provide as default polarized CMB maps from which all angular scales at l < 30 have been filtered out.

For each method we provide the following:

• Full-mission CMB intensity map, confidence mask and beam transfer function.
• Full-mission CMB polarisation map,
• A confidence mask.
• A beam transfer function.

In addition, and for characterisation purposes, we include six other sets of maps from three data splits: first/second half-ring, odd/even years and first/second half-mission. For the year-1,2 and half-mission-1,2 data splits we provide half-sum and half-difference maps which are produced by running the corresponding sums and differences inputs through the pipelines. The half-difference maps can be used to provide an approximate noise estimates for the full mission, but they should be used with caution. Each split has caveats in this regard: there are noise correlations between the half-ring maps, and missing pixels in the other splits. The Intensity maps are provided at Nside = 2048, at 5 arcmin resolution, while the Polarisation ones are provided at Nside = 1024, at 10 arcmin resolution. All maps are in units of K_cmb.

In addition, for each method we provide three sets of files, each categorized by the "R2.0X" label as follows:

R2.02

 This set of intensity and polarisation maps are provided at a resolution of Nside=1024. The Stokes Q and U maps are high-pass filtered to contain only modes above l > 30, as explained above and as used for analysis by the Planck Collaboration; THESE ARE THE POLARISATION MAPS WHICH SHOULD BE USED FOR COSMOLOGICAL ANALYSIS. Each type of map is packaged into a separate fits file (as for "R2.01"), resulting in file sizes which are easier to download (as opposed to the "R2.00" files), and more convenient to use with commonly used analysis software.

R2.01

This is the most complete set of 2015 CMB maps, containing Intensity products at a resolution of Nside=2048, and both Intensity and Polarisation at resolution of Nside=1024. For polarisation (Q and U), they contain all angular resolution modes. WE CAUTION USERS ONCE AGAIN THAT THE STOKES Q AND U MAPS ARE NOT CONSIDERED USEABLE FOR COSMOLOGICAL ANALYSIS AT l < 30. The structure of these files is the same as for "R2.02".

R2.00

 This set of files is equivalent to the "R2.01" set, but are packaged into only two large files. Warning: downloading these files could be very lengthy...

For a complete description of the above data structures, see below; the content of the first extensions is illustrated and commented in the table below.

The gallery below shows the Intensity, noise from half-mission, half-difference, and confidence mask for the four pipelines, in the order COMMANDER, NILC, SEVEM and SMICA, from top to bottom. The Intensity maps' scale is [–500.+500] μK, and the noise spans [–25,+25] μK. We do not show the Q and U maps since they have no significant visible structure to contemplate.

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  commander temperature

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  commander noise

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  commander mask

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  nilc temperature

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  nilc noise

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  nilc mask

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  sevem temperature

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  sevem noise

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  sevem mask

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  smica temperature

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  smica noise

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  smica mask

Product description

COMMANDER

Principle

COMMANDER is a Planck software code implementing pixel based Bayesian parametric component separation. Each astrophysical signal component is modelled in terms of a small number of free parameters per pixel, typically in terms of an amplitude at a given reference frequency and a small set of spectral parameters, and these are fitted to the data with an MCMC Gibbs sampling algorithm. Instrumental parameters, including calibration, bandpass corrections, monopole and dipoles, are fitted jointly with the astrophysical components. A new feature in the Planck 2015 analysis is that the astrophysical model is derived from a combination of Planck, WMAP and a 408 MHz (Haslam et al. 1982) survey, providing sufficient frequency support to resolve the low-frequency components into synchrotron, free-free and spinning dust. For full details, see Planck-2015-A10.

Resolution (effective beam)

The Commander sky maps have different angular resolutions depending on data products:

• The components of the full astrophysical sky model derived from the complete data combination (Planck, WMAP, 408 MHz) have a 1 degree FWHM resolution, and are pixelized at N_side=256. The corresponding CMB map defines the input map for the low-l Planck 2015 temperature likelihood.
• The Commander CMB temperature map derived from Planck-only observations has an angular resolution of ~5 arcmin and is pixelized at N_side=2048. This map is produced by harmonic space hybridiziation, in which independent solutions derived at 40 arcmin (using 30-857 GHz data), 7.5 arcmin (using 143-857 GHz data), and 5 arcmin (using 217-857 GHz data) are coadded into a single map.
• The Commander CMB polarization map has an angular resolution of 10 arcmin and is pixelized at N_side=1024. As for the temperature case, this map is produced by harmonic space hybridiziation, in which independent solutions derived at 40 arcmin (using 30-353 GHz data) and 10 arcmin (using 100-353 GHz data) are coadded into a single map.

Confidence mask

The Commander confidence masks are produced by thresholding the chi-square map characterizing the global fits, combined with direct CO amplitude thresholding to eliminate known leakage effects. In addition, we exclude the 9-year WMAP point source mask in the temperature mask. For full details, see Sections 5 and 6 in Planck-2015-A10. A total of 81% of the sky is admitted for high-resolution temperature analysis, and 83% for polarization analysis. For low-resolution temperature analysis, for which the additional WMAP and 408 MHz observations improve foreground constraints, a total of 93% of the sky is admitted.

NILC

Principle

The Needlet-ILC (hereafter NILC) CMB map is constructed both in total intensity as well as polarization: Q and U Stokes parameters. For total intensity, all Planck frequency channels are included. For polarization, all polarization sensitive frequency channels are included, from 30 to 353 GHz. The solution, for T, Q and U is obtained by applying the Internal Linear Combination (ILC) technique in needlet space, that is, with combination weights which are allowed to vary over the sky and over the whole multipole range.

Resolution (effective beam)

The spectral analysis, and estimation of the NILC coefficients, is performed up to a maximum [math]\ell=4000[/math]. The effective beam is equivalent to a Gaussian circular beam with FWHM=5 arcminutes.

Confidence mask

The same procedure is followed by SMICA and NILC for producing confidence masks, though with different parametrizations. A low resolution smoothed version of the NILC map, noise subtracted, is thresholded to 73.5 squared micro-K for T, and 6.75 squared micro-K for Q and U.

SEVEM

Principle

SEVEM produces clean CMB maps at several frequencies by using a procedure based on template fitting in real space. The templates are typically constructed from the lowest and highest Planck frequencies and then subtracted from the CMB-dominated channels, with coefficients that are chosen to minimize the variance of the clean map outside a considered mask. In the cleaning process, no assumptions about the foregrounds or noise levels are needed, rendering the technique very robust. Two single frequency clean maps are then combined to obtain the final CMB map.

Resolution

For intensity the clean CMB map is constructed up to a maximum [math]\ell=4000[/math] at Nside=2048 and at the standard resolution of 5 arcminutes (Gaussian beam).

For polarization the clean CMB map is produced at Nside=1024 with a resolution of 10 arcminutes (Gaussian beam) and a maximum [math]\ell=3071[/math].

Confidence masks

The confidence masks cover the most contaminated regions of the sky, leaving approximately 85 per cent of useful sky for intensity, and 80 per cent for polarization.

Foregrounds-subtracted maps

In addition to the regular CMB maps, SEVEM provides maps cleaned of the foregrounds for selected frequency channels (categorized as fgsub-sevem in the archive). In particular, for intensity there are clean CMB maps available at 100, 143 and 217 GHz, provided at the original resolution of the uncleaned channel and at Nside=2048. For polarization, there are Q/U clean CMB maps for the 70, 100 and 143 GHz (at Nside=1024). The 70 GHz clean map is provided at its original resolution, whereas the 100 and 143 GHz maps have a resolution given by a Gaussian beam with fwhm=10 arcminutes.

SMICA

Principle

SMICA produces CMB maps by linearly combining all Planck input channels with multipole-dependent weights. It includes multipoles up to [math]\ell = 4000[/math]. Temperature and polarization maps are produced independently.

Resolution (effective beam)

The SMICA intensity map has an effective beam window function of 5 arc-minutes which is truncated at [math]\ell=4000[/math] and is not deconvolved from the pixel window function. Thus the delivered beam window function is the product of a Gaussian beam at 5 arcminutes and the pixel window function for [math]N_{side}[/math]=2048.

The SMICA Q and U maps are obtained similarly but are produced at [math]N_{side}[/math]=1024 with an effective beam of 10 arc-minutes (to be multiplied by the pixel window function, as for the intensity map).

Confidence mask

A confidence mask is provided which excludes some parts of the Galactic plane, some very bright areas and masked point sources. This mask provides a qualitative (and subjective) indication of the cleanliness of a pixel. See section below detailing the production process.

Common Masks

A number of common masks have been defined for analysis of the CMB temperature and polarization maps. They are based on the confidence masks provided by the component separation methods. One mask for temperature and one mask for polarization have been chosen as the preferred masks based on subsequent analyses.

The common masks for the CMB temperature maps are:

• UT78: union of the Commander, SEVEM, and SMICA temperature confidence masks (the NILC mask was not included since it masks much less of the sky). It has f_sky = 77.6%. This is the preferred mask for temperature.

• UTA76: in addition to the UT78 mask, it masks pixels where standard deviation between the four CMB maps is greater than 10 μK. It has f_sky = 76.1%.

The common masks for the CMB polarization maps are:

• UP78: the union of the Commander, SEVEM and SMICA polarization confidence masks (the NILC mask was not included since it masks much less of the sky). It has f_sky = 77.6%.

• UPA77: In addition to the UP78 mask, it masks pixels where the standard deviation between the four CMB maps, averaged in Q and U, is greater than 4 μK. It has f_sky = 76.7%.

• UPB77: in addition to the UP78 mask, it masks polarized point sources detected in the frequency channel maps. It has f_sky = 77.4%. This is the preferred mask for polarization.

CMB-subtracted frequency maps ("Foreground maps")

These are the full-sky, full-mission frequency maps in intensity from which the CMB has been subtracted. The maps contain foregrounds and noise. They are provided for each frequency channel and for each component separation method. They are grouped into 8 files, two for each method of which there is one for each instrument. The maps are are at N_side = 1024 for the three LFI channels and at N_side = 2048 for the six HFI channels. The filenames are:

• LFI_Foregrounds-{method}_1024_Rn.nn.fits (145 MB each)
• HFI_Foregrounds-{method}_2048_Rn.nn.fits (1.2 GB each)

To remove the CMB, the respective CMB map was first deconvolved with the 5 arcmin beam, then convolved with the beam of the frequency channel, and finally subtracted from the frequency map. This was done using the [math]B_\rm{l}[/math] in harmonic space, assuming a symmetric beam.

The CMB-subtracted maps have complicated noise properties. The CMB maps contain a noise contribution from each of the frequency maps, depending on the weights with which they were combined. Therefore subtracting the CMB map from a frequency channel contributes additional noise from the other frequency channels.

Quadrupole Residual Maps

The second-order (kinematic) quadrupole is a frequency-dependent effect. During the production of the frequency maps the frequency-independent part was subtracted, which leaves a frequency-dependent residual quadrupole. The residuals in the component-separated CMB temperature maps have been estimated by simulating the effect in the frequency maps and propagating it through the component separation pipelines. The residuals have an amplitude of around 2 μK peak-to-peak. The maps of the estimated residuals can be used to remove the effect by subtracting them from the CMB maps.

Production process

COMMANDER

Pre-processing

All sky maps are first convolved to a common resolution that is larger than the largest beam of any frequency channel. For the combined Planck, WMAP and 408 MHz temperature analysis, the common resolution is 1 degree FWHM; for the Planck-only, all-frequency analysis it is 40 arcmin FWHM; and for the intermediate-resolution analysis it is 7.5 arcmin; while for the full-resolution analysis, we assume all frequencies between 217 and 857 GHz have a common resolution, and no additional convolution is performed. For polarization, only two smoothing scales are employed, 40 and 10 arcmin, respectively. The instrumental noise rms maps are convolved correspondingly, properly accouting for their matrix-like nature.

Priors

The following priors are enforced in the Commander analysis:

• All foreground amplitudes are enforced to be positive definite in the low-resolution analysis, while no amplitude priors are enforced in the high-resolution analyses
• Monopoles and dipoles are fixed to nominal values for a small set of reference frequencies
• Gaussian priors are enforced on spectral parameters, with values informed by the values derived in the high signal-to-noise areas of the sky
• The Jeffreys ignorance prior is enforced on spectral parameters in addition to the informative Gaussian priors

Fitting procedure

Given data and priors, Commander either maximizes, or samples from, the Bayesian posterior, P(theta|data). Because this is a highly non-Gaussian and correlated distribution, involving millions of parameters, these operations are performed by means of the Gibbs sampling algorithm, in which joint samples from the full distributions are generated by iteratively sampling from the corresponding conditional posterior distributions, P(theta_i| data, theta_{j/=i}). For the low-resolution analysis, all parameters are optimized jointly, while in the high-resolution analyses, which employs fewer frequency channels, low signal-to-noise parameters are fixed to those derived at low resolution. Examples of such parameters include monopoles and dipoles, calibration and bandpass parameters, thermal dust temperature etc.

NILC

Pre-processing

All sky frequency maps are deconvolved using the DPC beam transfer function provided, and re-convolved with a 5 arcminutes FWHM circular Gaussian beam. In polarization, prior to the smoothing process, all sky E and B maps are derived from Q and U using standard HEALPix tools from each individual frequency channels

Linear combination

Pre-processed input frequency maps are decomposed in needlet coefficients, specified in the Appendix B of the Planck A11 paper, with shape given by Table B.1. Minimum variance coefficients are then obtained, using all channels for T, from 30 to 353 for E and B.

Post-processing

E and B maps are re-combined into Q and U products using standard HEALPix tools.

SEVEM

The templates used in the SEVEM pipeline are typically constructed by subtracting two close Planck frequency channel maps, after first smoothing them to a common resolution to ensure that the CMB signal is properly removed. A linear combination of the templates [math]t_j[/math] is then subtracted from (hitherto unused) map d to produce a clean CMB map at that frequency. This is done in real space at each position on the sky: [math] T_c(\mathbf{x}, ν) = d(\mathbf{x}, ν) − \sum_{j=1}^{n_t} α_j t(\mathbf{x}) [/math] where [math]n_t[/math] is the number of templates. The [math]α_j[/math] coefficients are obtained by minimising the variance of the clean map [math]T_c[/math] outside a given mask. Note that the same expression applies for I, Q and U. Although we exclude very contaminated regions during the minimization, the subtraction is performed for all pixels and, therefore, the cleaned maps cover the full-sky (although we expect that foreground residuals are present in the excluded areas).

There are several possible configurations of SEVEM with regard to the number of frequency maps which are cleaned or the number of templates that are used in the fitting. Note that the production of clean maps at different frequencies is of great interest in order to test the robustness of the results, and these intermediate products (clean maps at individual frequencies for intensity and polarization) are also provided in the archive. Therefore, to define the best strategy, one needs to find a compromise between the number of maps that can be cleaned independently and the number of templates that can be constructed.

Intensity

For the CMB intensity map, we have cleaned the 100 GHz, 143 GHz and 217 GHz maps using a total of four templates. Three of them are constructed as the difference of two consecutive Planck channels smoothed to a common resolution (30-44, 44-70 and 545-353) while the 857 GHz channel is chosen as the fourth template. First of all, the six frequency channels which are going to be part of the templates are inpainted at the point source positions detected using the Mexican Hat Wavelet algorithm. The size of the holes to be inpainted is determined taking into account the beam size of the channel as well as the flux of each source. The inpainting algorithm is based on simple diffuse inpainting, which fills one pixel with the mean value of the neighbouring pixels in an iterative way. To avoid inconsistencies when subtracting two channels, each frequency map is inpainted on the sources detected in that map and on the second map (if any) used to construct the template. Then the maps are smoothed to a common resolution (the first channel in the subtraction is smoothed with the beam of the second map and viceversa). For the 857 GHz template, we simply filter the inpainted map with the 545 GHz beam.

The coefficients are obtained by minimising the variance outside the analysis mask, that covers the 1 per cent brightest emission of the sky as well as point sources detected at all frequency channels. Once the maps are cleaned, each of them is inpainted on the point sources positions detected at that (raw) channel. Then, the MHW algorithm is run again, now on the clean maps. A relatively small number of new sources are found and are also inpainted at each channel. The resolution of the clean map is the same as that of the original data. Our final CMB map is then constructed by combining the 143 and 217 GHz maps by weighting the maps in harmonic space taking into account the noise level, the resolution and a rough estimation of the foreground residuals of each map (obtained from realistic simulations). This final map has a resolution corresponding to a Gaussian beam of fwhm=5 arcminutes.

In addition, the clean CMB maps produced at 100, 143 and 217 GHz frequencies are also provided. The resolution of these maps is the same as that of the uncleaned frequency channels and have been constructed at Nside=2048. They have been inpainted at the position of the detected point sources. Note that these three clean maps should be close to independent, although some level of correlation will be present since the same templates have been used to clean the maps.

The confidence mask is produced by studying the differences between several SEVEM CMB reconstructions, which correspond to maps cleaned at different frequencies or using different analysis masks. The obtained mask leaves a useful sky fraction of approximately 85 per cent.

Polarization

To clean the polarization maps, a procedure similar to the one used for intensity data is applied to the Q and U maps independently. However, given that a narrower frequency coverage is available for polarization, the selected templates and maps to be cleaned are different. In particular, we clean the 70, 100 and 143 GHz using three templates for each channel. The first step of the pipeline is to inpaint the positions of the point sources using the MHW, in those channels which are going to be used in the construction of templates, following the same procedure as for the intensity case. The inpainting is performed in the frequency maps at their native resolution. These inpainted maps are then used to construct a total of four templates. To trace the synchrotron emission, we construct a template as the subtraction of the 30 GHz minus the 44 GHz map, after being convolved with the beam of each other. For the dust emission, the following templates are considered: 353-217 GHz (smoothed at 10' resolution), 217-143 GHz (used to clean 70 and 100 GHz) and 217-100 GHz (to clean 143 GHz). These two last templates are constructed at 1 degree resolution since an additional smoothing becomes necessary in order to increase the signal-to-noise ratio of the template. Conversely to the intensity case and due to the lower availability of frequency channels, it becomes necessary to use the maps to be cleaned as part of one of the templates. In this way, the 100 GHz map is used to clean the 143 GHz frequency channel and viceversa, making the clean maps less independent between them than in the intensity case.

These templates are then used to clean the non-inpainted 70 (at its native resolution), 100 (at 10' resolution) and 143 GHz maps (also at 10'). The corresponding linear coefficients are estimated independently for Q and U by minimising the variance of the clean maps outside a mask, that covers point sources and the 3 per cent brightest Galactic emission. Once the maps have been cleaned, inpainting of the point sources detected at the corresponding raw maps is carried out. The size of the holes to be inpainted takes into account the additional smoothing of the 100 and 143 GHz maps. The 100 and 143 GHz clean maps are then combined in harmonic space, using E and B decomposition, to produce the final CMB maps for the Q and U components at a resolution of 10' (Gaussian beam) for a HEALPix parameter Nside=1024. Each map is weighted taking into account its corresponding noise level at each multipole. Finally, before applying the post-processing HPF to the clean polarization data, the region with the brightest Galactic residuals is inpainted (5 per cent of the sky) to avoid the introduction of ringing around the Galactic centre in the filtering process.

The clean CMB maps at individual frequency channels produced as intermediate steps of SEVEM are also provided for Q and U, constructed at Nside=1024. The clean 70 GHz map is provided at its native resolution, while the clean maps at 100 and 143 GHz frequencies have a resolution of 10 arcminutes (Gaussian beam). The three maps have been inpainted in the positions of the detected point sources. Note that, due to the availability of a smaller number of templates for polarization than for intensity, these maps are less independent than for the temperature case, since, for instance, the 100 GHz map is used to clean the 143 GHz one and viceversa.

The confidence mask includes all the pixels above a given threshold in a smoothed version of the clean CMB map, the regions more contaminated by the CO emission and those pixels more affected by the high-pass filtering, leaving a useful sky fraction of approximately 80 per cent.

SMICA

A) Production of the intensity map.

1) Pre-processing

Before computing spherical harmonic coefficients, all input maps undergo a pre-processing step to deal with regions of very strong emission (such as the Galactic center) and point sources. The point sources with SNR > 5 in the PCCS catalogue are fitted in each input map. If the fit is successful, the fitted point source is removed from the map; otherwise it is masked and the hole is filled in by a simple diffusive process to ensure a smooth transition and mitigate spectral leakage. The diffusive inpainting process is also applied to some regions of very strong emissions. This is done at all frequencies but 545 and 857 GHz, here all point sources with SNR > 7.5 are masked and filled-in similarly.

2) Linear combination

The nine pre-processed Planck frequency channels from 30 to 857 GHz are harmonically transformed up to [math]\ell = 4000[/math] and co-added with multipole-dependent weights as shown in the figure.

3) Post-processing

A confidence mask is determined (see the Planck paper) and all regions which have been masked in the pre-processing step are added to it.

B) Production of the Q and U polarisation maps.

The SMICA pipeline for polarization uses all the 7 polarized Planck channels. The production of the Q and U maps is similar to the production of the intensity map. However, there is no input point source pre-processing of the input maps. The regions of very strong emission are masked out using an apodized mask before computing the E and B modes of the input maps and combining them to produce the E and B modes of the CMB map. Those modes are then used to synthesize the U and Q CMB maps. The E and B parts of the input frequency maps being processed jointly, there are, at each multipole, 2*7=14 coefficients (weights) defined to produce the E modes of the CMB map and as many to produce the B part. The weights are displayed in the figure below. The Q and U maps were originally produced at Nside=2048 with a 5-arc-minute resolution, but were downgraded to Nside=1024 with a 10 arc-minute resolution for this release.

Masks

Summary table with the different masks that have been used by the component separation methods to pre-process and to process the frequency maps and the CMB maps.

Commander 2015 (PR2)	Used for diffuse inpainting of input frequency maps	Used for constrained Gaussian realization inpaiting of CMB map	Description
T_MASK	NO	NO	T_MASK (the equivalent to PR1 VALMASK) is the confidence mask in temperature that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-commander-field-Int_2048_R2.01_full.fits.
P_MASK	NO	NO	P_MASK is the confidence mask in polarization that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-commander_1024_R2.02_full.fits.
INP_MASK_T	NO	YES	Three masks have been used for inpaiting of CMB maps for specific [math]\ell[/math] ranges: three different angular resolution maps (40 arcmin, 7.5 arcmin and full resolution), are produced using different data combinations and foreground models. Each of these are inpainted with their own masks with a constrained Gaussian realization before coadding the three maps in harmonic space. COM_Mask_PointSrcGalplane_commander_dx11d2_temp_n0256_lmax200_0256_R2.03.fits COM_Mask_PointSrcGalplane_commander_dx11d2_temp_lmax1000_2048_R2.03.fits COM_Mask_PointSrcGalplane_commander_dx11d2_temp_fullres_2048_R2.03.fits
INP_MASK_P	NO	YES	Mask used for inpainting of the CMB map in polarization. COM_Mask_PointSrcGalplane_commander_dx11d2_pol_fullres_1024_R2.02.fits
SEVEM 2015 (PR2)	Used for Diffuse Inpainting of foregorund subtracted CMB maps (fgsub-sevem)	Used for constrained Gaussian realization inpaiting of CMB map	Description
T_MASK	NO	NO	T_MASK (the equivalent to PR1 VALMASK) is the confidence mask in temperature that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-sevem-field-Int_2048_R2.01_full.fits.
P_MASK	NO	NO	P_MASK is the confidence mask in polarization that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-sevem_1024_R2.02_full.fits.
INP_MASK_T	YES	NO	Point source mask for temperature. This mask is the combination of the 143 and 217 T point source masks used for the inpainting of the foreground subtracted CMB maps at those two frequencies. These two maps have been combined to produce the final CMB map. COM_Mask_PointSrc_sevem_extended143x217_2048_R2.00.fits
INP_MASK_P	YES	NO	Point source mask for polarization. This mask is the combination of the 100 and 143 point source masks used for the inpainting of the foreground subtracted CMB maps at those two frequencies. These two maps have been combined to produce the final CMB map. COM_Mask_PointSrc_sevem_extended100x143_fw10_1024_R2.00.fits
INP_MASK_T for the cleaned 100, 143 and 217 GHz CMB	YES	NO	Three temperature point source masks used for the inpainting of the foreground subtracted CMB maps at the considered frequencies: COM_Mask_PointSrc_sevem_ps100_extended_2048_R2.00.fits (clean 100 GHz) COM_Mask_PointSrc_sevem_ps143_extended_2048_R2.00.fits (clean 143 GHz) COM_Mask_PointSrc_sevem_ps217_extended_2048_R2.00.fits (clean 217 GHz)
INP_MASK_P for the cleaned 70, 100 and 143 GHz CMB	YES	NO	Three polarization point source masks used for the inpainting of the foreground subtracted CMB maps at the considered frequencies: COM_Mask_PointSrc_sevem_dx11d_70_pol_varhole_full_99p90_1024_R2.00.fits (clean 70 GHz); COM_Mask_PointSrc_sevem_dx11d_100_pol_99.97pc_radius_3sigma_10arcmin_1024_R2.00.fits (clean 100 GHz) COM_Mask_PointSrc_sevem_dx11d_143_pol_99.97pc_radius_3sigma_10arcmin_1024_R2.00.fits (clean 143 GHz)
NILC 2015 (PR2)	Used for diffuse inpainting of input frequency maps	Used for constrained Gaussian realization inpaiting of CMB map	Description
T_MASK	NO	NO	T_MASK (the equivalent to PR1 VALMASK) is the confidence mask in temperature that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-nilc-field-Int_2048_R2.01_full.fits.
P_MASK	NO	NO	P_MASK is the confidence mask in polarization that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-nilc_1024_R2.02_full.fits.
INP_MASK	YES	NO	The pre-processing involves inpainting of the holes in INP_MASK in the frequency maps prior to applying NILC on them. The first mask (nside 2048) has been used for the pre-processing of sky maps for HFI channels and second one for LFI channels (nside 1024). They can downloaded here: COM_Mask_PointSrcGalplane_nilc_dx11_preproc_1024_R2.00.fits COM_Mask_PointSrcGalplane_nilc_dx11_preproc_2048_R2.00.fits
SMICA 2015 (PR2)	Used for diffuse inpainting of input frequency maps	Used for constrained Gaussian realization inpaiting of CMB map	Description
T_MASK	NO	YES	T_MASK (the equivalent to PR1 VALMASK) is the confidence mask in temperature that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-smica-field-Int_2048_R2.01_full.fits.
P_MASK	NO	YES	P_MASK is the confidence mask in polarization that defines the region where the reconstructed CMB is trusted. It can be found inside COM_CMB_IQU-smica_1024_R2.02_full.fits.
I_MASK	YES	NO	I_MASK, as in PR1, defines the regions over which CMB is not built. It is a combination of point source masks, Galactic plane mask and other bright regions like LMC, SMC, etc. It can downloaded here: COM_Mask_PointSrcGalplane_smica_harmonic_mask_2048_R2.00.fits

Inputs

The input maps are the sky temperature maps described in the Sky temperature maps section. SMICA and SEVEM use all the maps between 30 and 857 GHz; NILC uses the ones between 44 and 857 GHz. Commander-Ruler uses frequency channel maps from 30 to 353 GHz.

File names and structure

Three sets of files FITS files containing the CMB products are available. In the first set all maps (i.e., covering different parts of the mission) and all characterisation products for a given method and a given Stokes parameter are grouped into a single extension, and there are two files per method (smica, nilc, sevem, and commander), one for the high resolution data (I only, Nside=2048) and one for low resolution data (Q and U only, Nside=1024). Each file also contains the associated confidence mask(s) and beam transfer function. These are the R2.00 files which have names like

• COM_CMB_IQU-{method}-field-{Int,Pol}_Nside_R2.00.fits

There are 7 coverage periods:full, halfyear-1,2, halfmission-1,2, or ringhalf-1,2, and 4 characterisation products: half-sum and half-difference for the year and the half-mission periods.

In the second second set the different coverages are split into different files which in most cases have a single extension with I only (Nside=1024) and I, Q, and U (Nside=1024). This second set was built in order to allow users to use standard codes like spice or anafast on them, directly. So this set contains the I maps at Nside=1024, which are not contained in the R2.00; on the other hand this set does not contain the half-sum and half-difference maps. These are the 2.01 files which have names like

• COM_CMB_IQU-{method}{-field-Int|Pol}_Nside_R2.01_{coverage}.fits for the regular CMB maps, and
• COM_CMB_IQU-{fff}-{fgsub-sevem}{-field-Int|Pol}_Nside_R2.01_{coverage}.fits for the sevem frequency-dependent, foregrounds-subtracted maps,

where field-Int|Pol is used to indicate that only Int or only Pol data are contained (at present only field-Int is used for the high-res data), and is not included in the low-res data which contains all three Stokes parameters, and coverage is one of full, halfyear-1,2, halfmission-1,2, or ringhalf-1,2. Also, the coverage=full files contain also the confidence mask(s) and beam transfer function(s) which are valid for all products of the same method (one for Int and one for Pol when both are available).

The third set has the same structure as the Nside=1024 products of R2.01, but the Q and U maps have been high-pass filtered to remove modes at l < 30 for the reasons indicated earlier. These are the default products for use in polarisation studies. They are the R2.02 files which have names like:

• COM_CMB_IQU-{method}_1024_R2.02_{coverage}.fits

Version 2.00 files

These have names like

• COM_CMB_IQU-{method}-field-{Int,Pol}_Nside_R2.00.fits,

as indicated above. They contain:

• a minimal primary extension with no data;
• one or two BINTABLE data extensions with a table of Npix lines by 14 columns in which the first 13 columns is a CMB maps produced from the full or a subset of the data, as described in the table below, and the last column in a confidence mask. There is a single extension for Int files, and two, for Q and U, for Pol files.
• a BINTABLE extension containing the beam transfer function (mistakenly called window function in the files).

If Nside=1024 the files contain I, Q and U maps, whereas if Nside=2048 only the I map is given.

CMB R2.00 map file data structure

Ext. 1. or 2. EXTNAME = COMP-MAP (BINTABLE)
Column Name	Data Type	Units	Description
I or Q or U	Real*4	uK_cmb	I or Q or U map
HM1	Real*4	uK_cmb	Half-miss 1
HM2	Real*4	uK_cmb	Half-miss 2
YR1	Real*4	uK_cmb	Year 1
YR2	Real*4	uK_cmb	Year 2
HR1	Real*4	uK_cmb	Half-ring 1
HR2	Real*4	uK_cmb	Half-ring 2
HMHS	Real*4	uK_cmb	Half-miss, half sum
HMHD	Real*4	uK_cmb	Half-miss, half diff
YRHS	Real*4	uK_cmb	Year, half sum
YRHD	Real*4	uK_cmb	Year, half diff
HRHS	Real*4	uK_cmb	Half-ring half sum
HRHD	Real*4	uK_cmb	Half-ring half diff
MASK	BYTE		Confidence mask
Keyword	Data Type	Value	Description
AST-COMP	String	CMB	Astrophysical compoment name
PIXTYPE	String	HEALPIX
COORDSYS	String	GALACTIC	Coordinate system
POLCCONV	String	COSMO	Polarization convention
ORDERING	String	NESTED	Healpix ordering
NSIDE	Int	1024 or 2048	Healpix Nside
METHOD	String	name	Cleaning method (smica/nilc/sevem/commander)
Ext. 2. or 3. EXTNAME = BEAM_WF (BINTABLE) . See Note 1
Column Name	Data Type	Units	Description
BEAMWF	Real*4	none	The effective beam transfer function, including the pixel window function. See Note 2.
Keyword	Data Type	Value	Description
LMIN	Int	value	First multipole of beam TF
LMAX	Int	value	Last multipole of beam TF
METHOD	String	name	Cleaning method (SMICA/NILC/SEVEM/COMMANDER-Ruler)

Notes:

1. Actually this is a beam transfer function, so BEAM_TF would have been more appropriate.
2. The beam transfer function [math]B_\ell[/math] given here includes the pixel window function [math]p_\ell[/math] for the Nside=2048 pixelization. It means that, ideally, [math]C_\ell(map) = C_\ell(sky) \, B_\ell^2 \, p_\ell^2[/math]. The beam Window function is given by [math]W_\ell = B_\ell^2[/math]

Version 2.01 files

These files have names like:

• COM_CMB_IQU-{method}{-field-Int|Pol}_Nside_R2.01_{coverage}.fits for the regular CMB maps, and
• COM_CMB_IQU-{fff}-{fgsub-sevem}{-field-Int|Pol}_Nside_R2.01_{coverage}.fits for the sevem frequency-dependent, foregrounds-subtracted maps,

as indicated above. They contain:

• a minimal primary extension with no data, but with a NUMEXT keyword giving the number of extensions contained.
• one or two BINTABLE data extensions with a table of Npix lines by 1-5 columns depending on the file, as described above: the minimum begin I only, the maximum begin I, Q, U, and confidence masks for I and P.
• a BINTABLE extension containing the beam transfer function(s): one for I, and a second one that applies to both Q and U, if Nslde=1024.

If Nside=1024 the files contain I, Q and U maps, whereas if Nside=2048 only the I map is given. The basic structure, including information on the most important keywords, is given in the table below. For full details, see the FITS header.

CMB R2.01 map file data structure

Ext. 1. or 2. EXTNAME = COMP-MAP (BINTABLE)
Column Name	Data Type	Units	Description
I_Stokes	Real*4	uK_cmb	I map (Nside=1024,2048)
Q_Stokes	Real*4	uK_cmb	Q map (Nside=1024)
U_Stokes	Real*4	uK_cmb	U map (Nside=2048)
TMASK	Int	none	optional Temperature confidence mask
PMASK	Int	none	optional Polarisation confidence mask
Keyword	Data Type	Value	Description
AST-COMP	String	CMB	Astrophysical compoment name
PIXTYPE	String	HEALPIX
COORDSYS	String	GALACTIC	Coordinate system
POLCCONV	String	COSMO	Polarization convention
ORDERING	String	NESTED	Healpix ordering
NSIDE	Int	1024 or 2048	Healpix Nside
METHOD	String	name	Cleaning method (SMICA/NILC/SEVEM)
Optional Ext. 2. or 3. EXTNAME = BEAM_TF (BINTABLE)
Column Name	Data Type	Units	Description
INT_BEAM	Real*4	none	Effective beam transfer function. See Note 1.
POL_BEAM	Real*4	none	Effective beam transfer function. See Note 1.
Keyword	Data Type	Value	Description
LMIN	Int	value	First multipole of beam WF
LMAX_I	Int	value	Last multipole for Int beam TF
LMAX_P	Int	value	Last multipole for Pol beam TF
METHOD	String	name	Cleaning method

Notes:

1. The beam transfer function [math]B_\ell[/math] given here includes the pixel window function [math]p_\ell[/math] for the Nside=2048 pixelization. It means that, ideally, [math]C_\ell(map) = C_\ell(sky) \, B_\ell^2 \, p_\ell^2[/math]. The beam Window function is given by [math]W_\ell = B_\ell^2[/math]

Version 2.02 files

For polarisation work, this is the default set of files to be used for cosmological analysis. Their content is identical to the "R2.01" files, except that angular scales above l < 30 have been filtered out of the Q and U maps.

These files have names like:

• COM_CMB_IQU-{method}_1024_R2.02_{coverage}.fits

as indicated above. They contain: The files contain

• a minimal primary extension with no data, but with a NUMEXT keyword giving the number of extensions contained.
• one or two BINTABLE data extensions with a table of Npix lines by 1-5 columns depending on the file, as described above: the minimum begin I only, the maximum begin I, Q, U, and confidence masks for I and P.
• a BINTABLE extension containing 2 beam transfer functions: one for I and one that applies to both Q and U.

If Nside=1024 the files contain I, Q and U maps, whereas if Nside=2048 only the I map is given. The basic structure, including information on the most important keywords, is given in the table below. For full details, see the FITS header.

CMB R2.02 map file data structure

Ext. 1. or 2. EXTNAME = COMP-MAP (BINTABLE)
Column Name	Data Type	Units	Description
I_Stokes	Real*4	uK_cmb	I map (Nside=1024)
Q_Stokes	Real*4	uK_cmb	Q map (Nside=1024)
U_Stokes	Real*4	uK_cmb	U map (Nside=2048)
TMASK	Int	none	optional Temperature confidence mask
PMASK	Int	none	optional Polarisation confidence mask
Keyword	Data Type	Value	Description
AST-COMP	String	CMB	Astrophysical compoment name
PIXTYPE	String	HEALPIX
COORDSYS	String	GALACTIC	Coordinate system
POLCCONV	String	COSMO	Polarization convention
ORDERING	String	NESTED	Healpix ordering
NSIDE	Int	1024 or 2048	Healpix Nside
METHOD	String	name	Cleaning method (SMICA/NILC/SEVEM)
Optional Ext. 2. or 3. EXTNAME = BEAM_TF (BINTABLE)
Column Name	Data Type	Units	Description
INT_BEAM	Real*4	none	Effective beam transfer function. See Note 1.
POL_BEAM	Real*4	none	Effective beam transfer function. See Note 1.
Keyword	Data Type	Value	Description
LMIN	Int	value	First multipole of beam WF
LMAX_I	Int	value	Last multipole for Int beam TF
LMAX_P	Int	value	Last multipole for Pol beam TF
METHOD	String	name	Cleaning method

Notes:

1. The beam transfer function [math]B_\ell[/math] given here includes the pixel window function [math]p_\ell[/math] for the Nside=2048 pixelization. It means that, ideally, [math]C_\ell(map) = C_\ell(sky) \, B_\ell^2 \, p_\ell^2[/math]. The beam Window function is given by [math]W_\ell = B_\ell^2[/math]

Common masks

The common masks are stored into two different files for Temperature and Polarisation respectively:

• COM_CMB_IQU-common-field-MaskInt_2048_R2.nn.fits with the UT78 and UTA76 masks
• COM_CMB_IQU-common-field-MaskPol_1024_R2.nn.fits with the UP78, UPA77, and UPB77 masks

Both files contain also a map of the missing pixels for the half mission and year coverage periods. The 2 (for Temp) or 3 (for Pol) masks and the missing pixels maps are stored in 4 or 5 column a BINTABLE extension 1 of each file, named MASK-INT and MASK-POL, respectively. See the FITS file headers for details.

Quadrupole residual maps

The quadrupole residual maps are stored in files called:

• COM_CMB_IQU-kq-resid-{method}-field-Int_2048_R2.02.fits

They contain:

• a minimal primary extension with no data, but with a NUMEXT keyword giving the number of extensions contained.
• a single BINTABLE extension with a single column of Npix lines containing the HEALPIX map indicated

The basic structure of the data extension is shown below. For full details see the extension header.

Kinetic quadrupole residual map file data structure

Ext. 1. EXTNAME = COMP-MAP (BINTABLE)
Column Name	Data Type	Units	Description
INTENSITY	Real*4	K_cmb	the residual map
Keyword	Data Type	Value	Description
AST-COMP	String	KQ-RESID	Astrophysical compoment name
PIXTYPE	String	HEALPIX
COORDSYS	String	GALACTIC	Coordinate system
POLCCONV	String	COSMO	Polarization convention
ORDERING	String	NESTED	Healpix ordering
NSIDE	Int	2048	Healpix Nside
METHOD	String	name	Cleaning method