Difference between revisions of "Sky temperature maps"

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<span style="color:Red">NOTE: Text in red to be removed when filling the contents</span>
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==General description==
==Product description==
 
<span style="color:Red">A general description of the product, including e.g. figures related to the contents (e.g. maps, tables), and some explanation of its scientific meaning. If there are scientific warnings about the use of the product (User’s caveats), they should also be given here, or at least references to other explanatory documents (papers etc).</span>
 
  
Sky maps give the best estimate of the signal from the sky (unpolarised) after removal, as far as possible, of known systematic effects and of the dipole signals induced by the motion of the solar system in the CMB and of the Planck satellite in the solar system.  In particular, they include the Zodiacal light emission (Zodi for short) and also the scattering from the far-side lobes of the beams (FSL).  More on this below.
 
  
Sky maps are provided for the nominal Planck mission and for the first two single surveys, the third one being covered only for a small part during the nominal mission (REF). <span style="color:red">AMo: There is a table with table below that defines these coverage periods, but I believe that information should be in an earlier section that describes the mission and the events that interrupted it, the planet passages, the pointing, issues relating to timing, etc. That section should define a pointing period, and operational day, etc. There is some of that info in the HFI pre-processing section, but that may not be the best place for it.</span>For characterization purposes, are also provided maps covering the nominal survey but using only half of the available dataThese are the ''ringhalf_{1|2}'' maps, which are built using the first and second half of the stable pointing part of the data in each pointing period.
+
Sky maps give the best estimate of the intensity of the signal from the sky after removal, as far as possible, of known systematic effects and of the dipole signals induced by the motion of the solar system in the CMB and of the Planck satellite in the solar system.  Sky maps are provided for the nominal Planck mission and also, separately, for the first two single surveys, the third one being covered only for a small part during the nominal mission.The details of the start and end times of each are given in [[HFIpreprocessingstatics | this table]].   As a secondary product, maps with estimates of the Zodiacal light and Far-Side-Lobes contribution removed are also provided.   
  
{| border="1" cellpadding="5" cellspacing="0" align="center" style="text-align:center"
+
For characterization purposes, are also provided maps covering the nominal survey but each one using only half of the available data.  These are the ''ringhalf_{1|2}'' maps, which are built using the first and second half of the stable pointing part in each pointing period. These maps are used extensively to investigate the (high frequency) noise properties the maps themselves and of other products described elsewhere (see e.g., the [[HFI-Validation | data validation]] section).
|+ '''Missions and sky survey coverage periods'''
+
 
! width="80"| Name    !! Ini_OD  !! Ini_Ring !! Ini_ptgID  !!  End_OD !! End_ring !! End_ptgID
+
To help in further processing, there are also masks of the Galactic Plane and of point sources, each provided for several different depths.
|-
+
 
! align="left" | Nominal 
+
All sky maps are in Healpix format, with Nside of 2048 for HFI and of 1024 for LFI (note that the LFI 70 GHz has been delivered also at Nside of 2048 to be directly comparable with HFI maps), in Galactic coordinates, and Nested ordering. The signal is given in units of K<sub>cmb</sub> for 30-353 GHz, and of MJy/sr (for a constant $\nu F_\nu$ energy distribution ) for 545 and 857 GHz. Each sky map is packaged into a ''BINTABLE'' extension of a FITS file together with a hit-count map (or hit map, for short, giving the number of observation samples that are cumulated in a pixel, all detectors combined) and a variance map (determined from the half-ring maps), and additional information is given in the FITS file header. The structure of the FITS file is given in the [[#Format | FITS file structure]] section below.
|    91  ||    240  ||  00004200  ||    563  ||  14724  ||  03180200
+
 
|-
+
===Types of maps ===
! align="left" | HFI-Full
+
 
|    91  ||    240  ||  00004200  ||    993 || 27008  || 06344800
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; Full channel maps
|-
+
: Full channel maps are built using all the valid detectors of a frequency channel and cover the nominal mission. For HFI, the 143-8 and 545-3 bolometers are rejected entirely as they are seriously affected by RTS noise. The maps are displayed in the figures below. The range is the same from 30 - 143 GHz in order to show the CMB at the same level. At higher frequencies the range is increased in order to keep the Galactic Plane from invading the whole sky.
! align="left" | LFI-Full
 
|    91  ||    240  ||  00004200  ||  TBD  ||  TBD    ||  TBD
 
|-
 
! align="left" | SCAN1   
 
|    91  ||    240  ||  00004200  ||    270  ||  5720  ||  01059820
 
|-
 
! align="left" | SCAN2   
 
|  270  ||  5721  ||  01059830  ||    456  ||  11194  ||  02114520
 
|-
 
! align="left" | SCAN3
 
|  456  ||  11195  ||  02114530  ||    636  ||  16691  ||  03193660
 
|-
 
! align="left" | SCAN4 
 
|  636  ||  16692  ||  03193670  ||    807  ||  21720  ||  04243900
 
|-
 
! align="left" | SCAN5   
 
|  807  ||  21721  ||  95000020  ||    993  ||  27008  ||  06344800
 
|-
 
! align="left" | SCAN6   
 
|  993  || ----  ||  06344810 ||    993 ||  ----   || TBD 
 
|}
 
  
All sky maps are in Healpix format, with Nside of 2048 for HFI and of  1024 for LFI, in Galactic coordinates, and Nested ordering. The signal is given in units of K<sub>cmb</sub> for 33-353 GHz, and of MJy/sr (for a constant $\nu F_\nu$ energy distribution ) for 545 and 857 GHz. Each sky map is packaged into a ''BINTABLE'' extension of a FITS file together with a hit-count map (or hit map, for short) and a variance map, and additional information is given in the FITS file header. The structure of the FITS file is given in the [[#Format | FITS file structure]] section below.
+
<center>
 +
<gallery style="padding:0 0 0 0;" perrow=3 widths=260px heights=160px>  
 +
File: SkyMap30.png| '''Nominal mission, 30 GHz'''
 +
File: SkyMap44.png | '''Nominal mission, 44 GHz'''
 +
File: SkyMap70.png | '''Nominal mission, 70 GHz'''
 +
File: SkyMap100.png | '''Nominal mission, 100 GHz'''
 +
File: SkyMap143.png | '''Nominal mission, 143 GHz'''
 +
File: SkyMap217.png | '''Nominal mission, 217 GHz'''
 +
File: SkyMap353.png | '''Nominal mission, 353 GHz'''
 +
File: SkyMap545.png | '''Nominal mission, 545 GHz'''
 +
File: SkyMap857.png | '''Nominal mission, 857 GHz'''
 +
</gallery>
 +
</center>
  
==Production process==
+
; Single survey maps
<span style="color:Red">Description of the Pipeline used to generate the product. In particular any limitations and approximations used in the data processing should be listed. Avoiding detailed descriptions of methods and referring to other parts of the ES and/or the relevant Planck papers for the details. References however should be quite detailed (i.e. it is not enough to direct the user to a paper, but the relevant section in the paper should be provided).</span>
+
: Single survey maps are built using all valid detectors of a frequency channel; they cover separately the different sky surveys. The surveys are defined as the times over which the satellite spin axis rotates but 180 degrees, which, due to the position of the detectors in the focal plane does not cover the full sky, but a fraction between ~80 and 90% depending on detector position.
Sky maps are produced by combining appropriately the data of all working detectors in a frequency channel over some period of the mission. They give the best estimate of the signal from the sky (unpolarised) after removal, as far as possible, of known systematic effects and of the dipole signals induced by the motion of the solar system in the CMB and of the Planck satellite in the solar system.  In particular, they include the Zodiacal light emission (Zodi for short) and also the scattering from the far-side lobes of the beams (FSL).  More on this below.
 
=== HFI processing ===
 
  
The inputs to the mapmaking are TOIs of signal that have been cleaned (as far as possible) of instrumental effects and calibrated in absorbed watts. While the processing involved is described in detail in the [[TOI processing|TOI processing]] section, we give a very brief summary here for convenience. That pipeline performs the following operations:
+
; Detector set or detector pairs maps
 +
: These are maps built from a subset of the detectors in a frequency channel, typically our of two PSB pairs (i.e., four poloarisation-sensitive bolometers with different orientation on the sky), for HFI in order to extract a single temperature map. While none of these maps are part of the first Planck data release, the concept of ''detset'' is used, and thus it is worth mentioning it here. In particular, information by detector set is available at the [[Frequency_maps_angular_power_spectra | sky power spectrum]] level and in the [[The RIMO | RIMO]].
  
; demodulation: this is performed around a variable level which is determined from the valid input data (a validity flag from a previous version of the processing is used for this purpose), and the data are converted to engineering units (V) using known conversion coefficients.
+
; Half-ring maps
; despiking: using the demodulated data converted to V (by the transfer function) the glitches are identified and fitted with templates.  A glitch flag is produced that identifies the strongest part of the glitches, and a timeline of glitch tails is produced from the template fits, and subtracted from the demodulated timeline from step 1.  Finally, the flagged ranges are replaced with data from an average over the pointing period (TBC)
+
: Half-ring maps are built using only the first or the second half of the stable pointing period dataThere are thus two half-ring maps per frequency channel named ''ringhalf_1'' and ''ringhalf_2'' respectivelyThese maps are built for characterization purposes in order to perform null tests. In particular, the difference between the two half-ring maps at a given frequency give a good estimate of the high frequency noise in the data (albeit biased low by ~0.5% for the HFI channels due to specifics of the TOI processing).
; dark template removal: the two dark bolometers are demodulated and despiked as above; the resulting timelines are then smoothed and used as an indicator of the overall temperature variations of the bolometer plateWhere the variations are consistent with each other, they are combined and removed from the bolometer signal timelines using appropriate coupling coefficientsThe few percent of the data where they are not consistent are flagged on the timelines.
 
; conversion to absorbed power: the timeline is converted to watts of absorbed power using the bolometer function. This includes a non-linearity correction; removal of the 4K cooler lines: the electromagnetic interference of the 4K cooler with the bolometer readout wires induces some sharp lines in the signal power spectra at frequencies of the 4K cooler's fundamental and its multiples, folded by the signal modulations.  Fourier coefficients of the relevant lines are determined on a per-ring basis, and then removed from the data. The quality of the removal depends on the bolometer.
 
<!-- at this point a timeline in W and a glitch flag are stored to disk. The final two steps are: -->
 
; deconvolution by the time transfer function: this is done to correct for the non-instantaneous time response of the bolometers. The function itself is modeled using 4 parameters which are adjusted primarily on the planet data and also from comparisons of the  northward and southward scans of the Galactic Plane.  It is then removed using Fourier techniques, which has the side-effect of increasing the noise at high frequencies.
 
; jump correction: removes some (relatively rare: 0.3 jumps per bolometer per pointing period, on average) jumps in the signal baseline.  The jumps are detected characterized on smoothed TOIs, and corrected by adding a constant to part of the signal timeline. The origin of the jumps is not known.
 
  
The results of this processing are a timeline of signal (in absorbed watts) and a ''valid data'' flag timeline for each of the 50 valid bolometers processed; these timelines contain the full sky signal, i.e., including the solar and orbital dipoles, the Zodiacal light, and contributions from the Far-Side lobes. The dipoles are necessary for the flux calibration and are removed at the mapmaking stage.  The remaining two bolometers (143-8 and 535-3) show semi-random jumps in the signal level, typically jumping over 2-5 different ''pseudo-baseline'' levels, a behavior known as ''Random Telegraphic Signal'', so that these are commonly called the RTS bolometers. Finally, ring-level statistics of different types (mean, median, rms, kurtosis, etc.) are determined on a per-ring basis for all timelines, and a selection based on these statistics is used to discard anomalous rings, which are recorded in a ring-level flag for each valid bolometer timeline.
+
; Masks
 +
: Masks are provided of the Galactic Plane and of the point sources. For the Galactic Plane, eight masks are given covering different fractions of the sky, and for the points sources two masks are given, at the 5 and 10 sigma level, for each Planck HFI frequency channel. These are generic masks, specific masks applicable to other products are delivered with the products themselves.
  
Throughout this processing, bright planets (Mars, Jupiter, Saturn, Uranus) and bright asteroids are masked in the timeline in order to avoid ringing effects in the processing.  Since they move on the sky, the portion of the sky masked during one survey is observed during one, and no hole is left in the final map.  In parallel, the planet data are processed in a similar way, but with different parameters for the despiking step, and without the final jump correction step.  These results are processed separately to determine the beam shapes and the focal plane geometry.
+
=== Caveats and known issues ===
  
 +
The primary limitation of the HFI maps are
 +
* the absence of correction of the ADC non-linearities,
 +
* the far-side lobe contribution is not accounted for in the processing and in the calibration,
 +
* the dipole removal is based on the non-relativistic approximation which leaves a weak quadrupole component in the map.
 +
And thus the overall calibration accuracy is at the 0.2% level in 100-217 GHz channels
  
The pointing is determined starting from the AHF produced by MOC, which gives the direction and orientation of the LOS of a fiducial position in the focal plane at frequencies of 8Hz during stable pointing and 4 Hz during maneuvers (TBC for details, reference). This is interpolated to the times of data observation (ref to method), corrected for the wobble and other time-dependent offsets determined from the observed positions of a large number of sources around the sky, and finally converted to the LOS of each detector using the quaternions in the IMO (which are determined from observations of bright planets - see the Focal plane reconstruction pipeline).  
+
The LFI 70 GHz maps at Nside=2048 should be considered as additional product, the default are the LFI maps at Nside=1024. No effective beam at Nside=2048 is provided, only at Nside=1024, for this reason the use of the effective beam with maps at Nside 2048 is discouraged.
  
 +
==== Map zero-level ====
  
The mapmaking pipeline is described in detail in the [[Map-making_LFI | Map-making]] section, and a brief summary is given here for convenience.
+
For the  100 to 857 GHz maps, the zero levels are set to their optimal levels for Galactic and CIB studies.  A procedure for adjusting them to astrophysical values is given in the HFI Calibration paper {{PlanckPapers|planck2013-p03b}}.
  
The cleaned TOIs of signal of each detector, together with their flags, produced by the [[TOI processing|TOI processing]] pipeline, and the TOIs of pointing (quaternions), described in [[Pointing&Beams | Detectors pointing and beams]], are the inputs to the mapmaking step.  
+
For the 30, 44 and 70 GHz, maps are corrected for zero level monopole by applying an offset correction, see LFI Calibration paper {{PlanckPapers|planck2013-p02b}} section 3.4 "Setting the zero levels in the maps". Note that the offset applied is indicated in the header as a comment keyword.
  
The input signal TOIs are expressed in Watts from the sky absorbed by the bolometer, and their associated flags are used to samples or full rings to discard. Are discarded periods of unstable pointing and pointing maneuvers in general, glitched data, transits over bright planets (since they move, the ''hole'' flagged during one survey is covered during another sky survey), and some full rings are discarded if their noise properties differ significantly from the nominal value and the few rings of duration longer than 90 min, since the pointing is not sufficiently stable over such long periods (details in [[TOI_processing#Discarded_rings| Discarded rings]] section). The preparation of input pointing TOIs is described in [[Pointing&Beams | Detectors pointing and beams]].  In brief, the STR (StarTracker) pointing produced by Flight Dynamics is interpolated to the detector sampling frequency in order to obtain a tuple of pointing quaternions for each sample and corrected for certain known effects. The angular offset between the STR line of sight and that of each bolometer is reflected in the Focal Plane Geometry, which is determined from the observation of bright planets. Also, the STR pointing timeline is corrected for slowly varying offsets between the STR and the HFI focal plane using observations of all planets and of other (fixed) bright sources.
+
==== The Zodiacal light and the Far-Side Lobes ====
  
Using the pointing TOIs, the signal TOIs are first used to build Healpix rings using the nearest grid point method; each ring containing the combined data of one pointing period. These are then calibrated in brightness, cleaned of the dipole signals, and projected onto Healpix maps as explained in the following sections.  
+
The figures below show the modeled Zodiacal light and Far Side Lobes projected onto the maps; they are simply the difference between the ''main product'' and the ''ZodiCorrected'' maps for the nominal mission.  The units are given in the figures.  The ''heat'' color table has been used in place of the standard Planck for clarity reasons. 
 +
<center>
 +
<gallery perrow=3 widths=260px heights=170px>
 +
File: ZodiRes100.png | '''zodi/FSL rediduals - 100 GHz'''
 +
File: ZodiRes143.png | '''zodi/FSL rediduals - 143 GHz'''
 +
File: ZodiRes217.png | '''zodi/FSL rediduals - 217 GHz'''
 +
File: ZodiRes353.png | '''zodi/FSL rediduals - 353 GHz'''
 +
File: ZodiRes545.png | '''zodi/FSL rediduals - 545 GHz'''
 +
File: ZodiRes857.png | '''zodi/FSL rediduals - 857 GHz'''
 +
</gallery>
 +
</center>
 +
The effects of the FSLs are seen most clearly at the highest frequencies, as structures roughly symmetric about the center of the image, which corresponds to the location of the Galactic Centre, which is in turn the source of most of the radiation that is scattered into the FSLs.
  
The cleaned TOIs must be calibrated in astrophysical units.  At 100-353 GHz, the flux calibration gains are determined for each pointing period (or ring) from the solar-motion dipole after removal of the small dipole induced by the motion of the Planck satellite in the solar system. The solar-motion dipole from WMAP (REF) is used for this purpose.  This gain by ring is then smoothed with a window of width 50 rings, which reveals an apparent variation of ~1-2% on a scale of 100s to 1000s of rings for the 100-217 GHz channels, and is applied to the Watt data.  At 353GHz, where the solar motion dipole is weaker compared to the signal, no gain variation is detected, and a single fixed gain is applied to all rings.  At 545 and 857 GHz the gain is determined from the observation of Uranus and Neptune (Jupiter is not used because its brightness produced some non-linearity in the bolometer response) and comparison to recent models (REF) made explicitly for this mission.  A single gain is applied to all rings at these frequencies.
+
==== Artifacts near caustics of the scanning strategy ====
Prior to projecting the Healpix rings (HPRs) onto a map, a destriping approach is used to remove low-frequency noise.  The noise is  modelled as the sum of a white noise component and a constant, or ''offset'', per pointing period which represents the low frequency 1/f noise. The offsets are determined by minimizing the differences between  HPRs at their crossings.  After subtracting these offsets, calibrated data are projected onto Healpix maps, with the data of each bolometer weighted by a factor of 1/NET of that bolometer, and accounting for the slight different band transmission profiles of the bolometers in each band.
 
  
These maps provide the main mission products.  A second, reduced, set of maps, cleaned of the Zodiacal emission of the FSL leakage is also produced for the nominal mission and the two single surveys, but not for the half-rings (since the contribution would be the same for the two halves of each ring).  For this purpose, the the Zodiacal emission and the FSL contamination, which are not fixed on the sky, are modeled separately at HPR-level, and subtracted from the signal HPR before projecting them onto the maps.  
+
The [[Survey scanning and performance|scanning strategy]] is such that regions around the Ecliptic poles are surveyed very deeply and compared to the average, and the transition from the nominal depth to the high depth, as shows on hit-count maps is very rapid, namely a few pixels, for a contrast of ~30.  These transitions, or caustics in the maps, occur at different positions on the sky for different detectors, as the positions depend on their location in the focal plane of the instrument.  As a result, when data from different detectors are combined to build a full channel map, the the weights of different detectors in the mix changes rapidly across the caustic, and given the remaining errors in the relative calibration of the detectors, a visible effect can be introduced in the maps, especially when the SNR is very high, i.e. at the highest frequencies and near bright regions like the Galactic Plane.  Some examples are shown below.
  
Together with signal maps, hit count and variance maps are also produced. The hit maps give the (integer) number of valid TOI-level samples that contribute to the signal of each pixel. All valid samples are counted in the same way, i.e., there is no weighting factor appliedThe variance maps project the white noise estimate, provided by the NETs, in the sky domain.
+
<center>
 +
<gallery perrow=3 heights=260px  widths=260pix >
 +
File: causta857.png | '''857 GHz intensity map around (272.5, -27)'''
 +
File: caustb857.png | '''857 GHz intensity map around (264.5, -37.5)'''
 +
File: caustc857.png | '''857 GHz intensity map around (98.5, 43)'''
 +
File: hita857.png  | '''857 GHz hit count map around (272.5, -27)'''
 +
File: hitb857.png | '''857 GHz hit count map around (264.5, -37.5)'''
 +
File: hitc857.png  | '''857 GHz hit count map around (98.5, 43)'''
 +
</gallery>
 +
</center>
  
=== LFI processing ===
+
==Production process==
  
LFI processing is covered in Sect. 4.5
 
  
==Inputs==
+
Sky maps are produced by combining appropriately the data of all working detectors in a frequency channel over some period of the mission. They give the best estimate of the signal from the sky (unpolarised) after removal, as far as possible, of known systematic effects and of the dipole signals induced by the motion of the solar system in the CMB and of the Planck satellite in the solar system. In particular, they include the Zodiacal light emission (Zodi for short) and also the scattering from the far-side lobes of the beams (FSL)More on this below.
<span style="color:Red">A list (and brief description to the extent possible) of the input data used to generate this product (down to file names), as well as any external ancillary data sets which were used.</span>
 
==Related products==
 
<span style="color:Red">A description of other products that are related and share some commonalities with the product being described here. E.g. if the description is of a generic product (e.g. frequency maps), all the products falling into that type should be listed and referenced.</span>
 
==Format==
 
<span style="color:Red">A detailed description of the data format of each file, including header keywords for fits files, extension names, column names, formats….</span>
 
===File names===
 
The FITS filenames are of the form ''{H|L}FI_SkyMap_fff_nnnn_R1.nn_{type}_{coverage}_{type}.fits'', where ''fff'' are three digits to indicate the Planck frequency band, and ''nnnn'' is the Healpix Nside of the map, ''coverage'' indicates which part of the mission is covered, and the optional ''type'' indicates the subset of input data usedA full list of products, by their names, is given in the [[#List of products | List of products]] below.  
 
===Extensions===
 
===Keywords===
 
===Numerical Format===
 
  
== Introduction ==
+
=== HFI processing ===
  
 +
The inputs to the mapmaking are TOIs of signal that have been cleaned (as far as possible) of instrumental effects and calibrated in absorbed watts. While the processing involved is described in detail in the [[TOI processing|TOI processing]] section, we give a very brief summary here for convenience. That pipeline performs the following operations:
  
 +
; demodulation: this is performed around a variable level which is determined from the valid input data (a validity flag from a previous version of the processing is used for this purpose), and the data are converted to engineering units (V) using known conversion coefficients.
 +
; despiking: using the demodulated data converted to V (by the transfer function) the glitches are identified and fitted with templates.  A glitch flag is produced that identifies the strongest part of the glitches, and a timeline of glitch tails is produced from the template fits, and subtracted from the demodulated timeline from step 1.  Finally, the flagged ranges are replaced with data from an average over the pointing period (TBC)
 +
; dark template removal: the two dark bolometers are demodulated and despiked as above; the resulting timelines are then smoothed and used as an indicator of the overall temperature variations of the bolometer plate.  Where the variations are consistent with each other, they are combined and removed from the bolometer signal timelines using appropriate coupling coefficients.  The few percent of the data where they are not consistent are flagged on the timelines.
 +
; conversion to absorbed power: the timeline is converted to watts of absorbed power using the bolometer function.  This includes a non-linearity correction; removal of the 4K cooler lines: the electromagnetic interference of the 4K cooler with the bolometer readout wires induces some sharp lines in the signal power spectra at frequencies of the 4K cooler's fundamental and its multiples, folded by the signal modulations.  Fourier coefficients of the relevant lines are determined on a per-ring basis, and then removed from the data. The quality of the removal depends on the bolometer.
 +
; deconvolution by the time transfer function: this is done to correct for the non-instantaneous time response of the bolometers. The function itself is modeled using 4 parameters which are adjusted primarily on the planet data and also from comparisons of the  northward and southward scans of the Galactic Plane.  It is then removed using Fourier techniques, which has the side-effect of increasing the noise at high frequencies.
 +
; jump correction: removes some (relatively rare: 0.3 jumps per bolometer per pointing period, on average) jumps in the signal baseline.  The jumps are detected characterized on smoothed TOIs, and corrected by adding a constant to part of the signal timeline. The origin of the jumps is not known.
  
 +
The results of this processing are a timeline of signal (in absorbed watts) and a ''valid data'' flag timeline for each of the 50 valid bolometers processed; these timelines contain the full sky signal, i.e., including the solar and orbital dipoles, the Zodiacal light, and contributions from the Far-Side lobes. The dipoles are necessary for the flux calibration and are removed at the mapmaking stage.  The remaining two bolometers (143-8 and 535-3) show semi-random jumps in the signal level, typically jumping over 2-5 different ''pseudo-baseline'' levels, a behavior known as ''Random Telegraphic Signal'', so that these are commonly called the RTS bolometers.  Finally, ring-level statistics of different types (mean, median, rms, kurtosis, etc.) are determined on a per-ring basis for all timelines, and a selection based on these statistics is used to discard anomalous rings, which are recorded in a ring-level flag for each valid bolometer timeline (see the [[TOI_processing#Discarded_rings| Discarded rings]] section). 
  
 +
Throughout this processing, bright planets (Mars, Jupiter, Saturn, Uranus) and bright asteroids are masked in the timeline in order to avoid ringing effects in the processing.  Since they move on the sky, the portion of the sky masked during one survey is observed during one, and no hole is left in the final map.  In parallel, the planet data are processed in a similar way, but with different parameters for the despiking step, and without the final jump correction step.  These results are processed separately to determine the beam shapes and the focal plane geometry.
  
 +
The pointing is determined starting from the AHF produced by MOC, which gives the direction and orientation of the LOS of a fiducial position in the focal plane at frequencies of 8Hz during stable pointing and 4 Hz during maneuvers (TBC for details, reference).  This is interpolated to the times of data observation (ref to method), corrected for the wobble and other time-dependent offsets determined from the observed positions of a large number of sources around the sky, and finally converted to the LOS of each detector using the quaternions in the IMO (which are determined from observations of bright planets - see the [[Detector_pointing]] section).
  
 +
The mapmaking and calibration process is described in detail in the [[Map-making_LFI | Map-making]] section, where detailed references are found.  In brief it consists of:
  
 +
; binning the TOI data onto ''rings'' : Healpix rings (HPRs) are used here, each ring containing the combined data of one pointing period.
 +
; flux calibration : at 100-353 GHz, the flux calibration factors are determined for each pointing period (or ring) from the solar-motion dipole, using the WMAP dipole as the reference, and after removal of the dipole signal induced by the motion of the Planck satellite in the solar system.  This gain by ring is smoothed with a window of width 50 rings, which reveals an apparent variation of ~1-2% on a scale of 100s to 1000s of rings for the 100-217 GHz channels, and is applied.  At 353GHz, where the solar motion dipole is weaker compared to the signal, no gain variation is detected (within the uncertainties), and a single fixed gain is applied to all rings.  At 545 and 857 GHz the gain is determined from the observation of Uranus and Neptune (but not Jupiter which is too bright) and comparison to recent models made explicitly for this mission.  A single gain is applied to all rings at these frequencies.
 +
; destriping : in order to remove low-frequency noise, an offset per ring is determined by minimizing the differences between HPRs at their crossings, and removed.
 +
; projection onto the map : the offset-corrected and flux-calibrated HPRs are projected onto Healpix maps, with the data of each bolometer weighted by a factor of 1/NET of that bolometer, and accounting for the slight different band transmission profiles of the bolometers in each band.
  
All sky maps are in Healpix format, with Nside of 2048 for HFI and of  1024 for LFI, in Galactic coordinates, and Nested ordering. The signal is given in units of K<sub>cmb</sub> for 33-353 GHz, and of MJy/sr (for a constant $\nu F_\nu$ energy distribution ) for 545 and 857 GHzEach sky map is packaged into a ''BINTABLE'' extension of a FITS file together with a hit-count map (or hit map, for short) and a variance map, and additional information is given in the FITS file header.  The structure of the FITS file is given in the [[#FITS file structure | FITS file structure]] section below.  
+
These maps provide the main mission products.  A second, reduced, set of maps, cleaned of the Zodiacal emission of the FSL leakage is also produced for the nominal mission and the two single surveys, but not for the half-rings (since the contribution would be the same for the two halves of each ring).  For this purpose, the the Zodiacal emission and the FSL contamination, which are not fixed on the sky, are modeled separately at HPR-level, and subtracted from the signal HPR before projecting them onto the maps.  
  
The FITS filenames are of the form ''{H|L}FI_SkyMap_fff_nnnn_R1.nn_{type}_{coverage}_{type}.fits'', where ''fff'' are three digits to indicate the Planck frequency band, and ''nnnn'' is the Healpix Nside of the map, ''coverage'' indicates which part of the mission is covered, and the optional ''type'' indicates the subset of input data usedA full list of products, by their names, is given in the [[#List of products | List of products]] below.  
+
Together with signal maps, hit count and variance maps are also produced. The hit maps give the (integer) number of valid TOI-level samples that contribute to the signal of each pixel. All valid samples are counted in the same way, i.e., there is no weighting factor appliedThe variance maps project the white noise estimate, provided by the NETs, in the sky domain.
  
 +
=== LFI processing ===
  
 +
LFI maps were constructed with the Madam map-making code, version 3.7.4. The code is based on generalized destriping technique, where the correlated noise component is modeled as a sequence of constant offset,  called baselines. A noise filter was used to constrain the baseline solution allowing the use of 1 second baselines.
  
 +
Radiometers were combined according to the horn-uniform weighting scheme to minimize systematics. The used weights are listed in [[Map-making LFI#Map-making|Map-making]]. The flagged samples were excluded from the analysis by setting their weights to $C_{w}^{-1}$ = 0. The galaxy region was masked out in the destriping phase, to reduce error arising from strong signal gradients. The polarization component was included in the analysis, although only the temperature maps are released.
  
 +
A detailed description of the map-making procedure is given in {{PlanckPapers|planck2013-p02}} and in section [[Map-making LFI#Map-making|Map-making]].
  
 +
==Inputs==
  
  
=== Selected images ===
+
=== HFI inputs ===
  
<span style="color:red">Insert here some images: </span>
+
* The cleaned TOIs of signal of each detector, together with their flags, produced by the [[TOI processing|TOI processing]] pipeline
 +
* The TOIs of pointing (quaternions), described in [[Detector_pointing]]
 +
* Bolometer-level characterization data, from the DPC's internal IMO (not distributed)
 +
* Planck orbit data used to compute and remove the earth dipole
 +
* WMAP solar dipole information used to calibrate the CMB channels
 +
* Planet models used to calibrate the Galactic channels.
  
 +
=== LFI inputs ===
  
== Types of maps ==
+
The Madam map-maker takes as an input:
  
=== Full channel maps ===
+
* The calibrated timelines (for details see [[TOI processing LFI|TOI Processing]])
 +
* The detector pointings (for details see [[Detector pointing|Detector pointing]])
 +
* The noise information in the form of three-parameter (white noise level ($\sigma$), slope, and knee frequency ($f_\mathrm{knee}$)) noise model (for details see  [[The RIMO|RIMO]])
  
Full channel maps are built using all the valid detectors of a frequency channel and cover the full mission (or the nominal mission for the 1st release).  For HFI, the 143-8 and 545-3 bolometers are rejected entirely as they are seriously affected by RTS noise.
+
==Related products==
  
=== Single survey maps ===
 
  
Single survey maps are built using all valid detectors of a frequency channel, but cover separately the different sky surveys.  The single sky surveys are defined in terms of the direction of the satellite's spin axis:  the first survey covers from the beginning of the science observations (the First Light Survey) to the time when the spin axis has rotated by 180 degrees (to the nearest pointing period), the following ones covers from 180 to 360, and so on.  In the case of the nominal mission, the process stops at the third survey, which is incomplete.  In the case of the full mission the 4th survey was interrupted shortly before completing the 180 degree rotation (see LINK), in order to begin observing with a different scanning law.  The HFI mission ended slightly before the natural end of the 5th survey, the LFI mission continued to the XXX survey.  The coverage of each of these periods in terms of ring number, pointingID, and OD, is given in the table below. Note that the OD numbers are only to indicate during which OD the period boundary occurs.
+
=== Masks ===
  
=== Half-ring maps ===
+
Masks are provided of
  
Half-ring maps are built using only the first or the second half of the stable pointing period data.  There are thus two half-ring maps per frequency channel named ''ringhalf_1'' and ''ringhalf_2'' respectively. These maps are built for characterization purposes in order to perform null tests. In particular, the difference between the two half-ring maps at a given frequency give a good estimate of the high frequency noise in the data.
+
; the point sources
 +
: 15 masks are provided, three for the LFI (one mask for each frequency masking at the 4<math>\sigma</math> level) and 12 for the HFI (two masks for each frequency at the 5 and 10<math>\sigma</math> levels. For the HFI the masks can be used as they are, for the LFI they need to be downgraded to Nside=1024 except for the 70 GHz channel at Nside=2048 which does not need to be downgraded.
  
=== Caveats and known issues ===
+
; the Galactic Plane
 +
: 8 masks are provided giving 20, 40, 60, 70, 80, 90, 97, and 99% sky coverage in two different files, at Nside=2048. For the HFI they can be used as they are, for the LFI they need to be downgraded at Nside=1024 (note that if using the 70 GHZ at Nside=2048 no downgraded is needed)
  
==== Map zero-level ====
 
  
* not corrected for HFI; estimates are ??? determined from ????
+
The masks are binary, in GALACTIC coordinates, and NESTED ordering. The table below give the filenames. 
* corrected for LFI (values?)
 
  
==== The Zodiacal light and the Far-Side Lobes ====
 
  
<span style="color:red">Insert here how these are seen in the differences of the single survey maps </span>
+
{| class="wikitable"  align="center" style="text-align:center" border="1" cellpadding="5" cellspacing="0"
 +
|+ '''FITS filenames for masks'''
 +
|-bgcolor="ffdead"
 +
! Frequency || LFI Point Source masks
 +
|-
 +
| '''30GHz'''  || {{PLASingleFile|fileType=map|name=LFI_MASK_030-ps_2048_R1.00.fits|link=LFI_MASK_030-ps_2048_R1.00.fits}}
 +
|-
 +
| '''44GHz'''  || {{PLASingleFile|fileType=map|name=LFI_MASK_044-ps_2048_R1.00.fits|link=LFI_MASK_044-ps_2048_R1.00.fits}}
 +
|-
 +
| '''70GHz'''  || {{PLASingleFile|fileType=map|name=LFI_MASK_070-ps_2048_R1.00.fits|link=LFI_MASK_070-ps_2048_R1.00.fits}}
 +
|- bgcolor="ffdead"
 +
! colspan="2" | HFI Point Source masks
 +
|-
 +
| colspan="2" | {{PLASingleFile|fileType=map|name=HFI_Mask_PointSrc_2048_R1.10.fits|link=HFI_Mask_PointSrc_2048_R1.10.fits}}
 +
|- bgcolor="ffdead"
 +
! colspan="2" | Galactic Plane masks
 +
|-
 +
| colspan="2" | {{PLASingleFile|fileType=map|name=HFI_Mask_GalPlane_2048_R1.10.fits|link=HFI_Mask_GalPlane_2048_R1.10.fits}}
 +
|}
  
==== Artifacts near caustics of the scanning strategy ====
 
  
TBW if still an issue??
+
The masks are shows below in a single figure.  While this is quite clear for the Galactic Plane masks, it is less so for the point source masks, but it does give a clear perspective on how the latter are distributed over the sky.
  
 +
<center>
 +
<gallery perrow=2 widths=300px heights=185px >
 +
File: HFI_GalPlaneMask.png |  '''Galactic Plane masks'''
 +
File: HFI_PointSrcMask.png  | '''PointSource masks'''
 +
</gallery>
 +
</center>
  
 +
== File names ==
  
<!--- NOT FOR 1st RELEASE … put detset table elsewhere ????
 
  
  === Detector-set maps ===
+
The FITS filenames are of the form ''{H|L}FI_SkyMap_fff_nnnn_R1.nn_{coverage}_{type}.fits'', where ''fff'' are three digits to indicate the Planck frequency band, and ''nnnn'' is the Healpix Nside of the map, ''coverage'' indicates which part of the mission is covered, and the optional ''type'' indicates the subset of input data used. A full list of products, with links to them in the Archive, is given in the tables below.
  
Detector-set (detset) maps are built for the full (or nominal) mission using a minimal set of detectors.  This concept is applicable to polarization maps, which are built using two PSB pairs at the proper orientations. The HFI polarized channels are designed to provide two detsets (or quads) each, namely:
+
For the benefit of users who are only looking for the frequency maps with no additional information, we also provide a file combining the 9 frequency maps as separate columns in a single extension. The 9 columns in this file contain the intensity maps ONLY and no other information (hit maps and variance maps) is provided.
  
{| class="wikitable"  align="center" style="text-align:center" border="1" cellpadding="5" cellspacing="0"  
+
{| class="wikitable"  align="center" style="text-align:center" border="1" cellpadding="5" cellspacing="0" width=500px
|+ '''HFI detector sets or quads'''
+
|+ '''FITS filenames'''
| '''100–ds1:''' 100-1a,100-1b,100-4a,100-4b || '''100–ds2:''' 100-2a,100-2b,100-3a,100-3b
+
|- bgcolor="ffdead"
 +
! Frequency || Full channel maps
 +
|-
 +
| '''30GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_030_1024_R1.10_nominal.fits|link=LFI_SkyMap_030_1024_R1.10_nominal.fits}}
 +
|-
 +
| '''44GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_044_1024_R1.10_nominal.fits|link=LFI_SkyMap_044_1024_R1.10_nominal.fits}}
 +
|-
 +
| '''70GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_070_1024_R1.10_nominal.fits|link=LFI_SkyMap_070_1024_R1.10_nominal.fits}}
 +
|-
 +
| '''70GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_070_2048_R1.10_nominal.fits|link=LFI_SkyMap_070_2048_R1.10_nominal.fits}}
 +
|-
 +
| '''100GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_nominal.fits|link=HFI_SkyMap_100_2048_R1.10_nominal.fits}}
 +
|-
 +
| '''143GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_nominal.fits|link=HFI_SkyMap_143_2048_R1.10_nominal.fits}}
 +
|-
 +
| '''217GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_nominal.fits|link=HFI_SkyMap_217_2048_R1.10_nominal.fits}}
 +
|-
 +
| '''353GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_nominal.fits|link=HFI_SkyMap_353_2048_R1.10_nominal.fits}}
 +
|-
 +
| '''545GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_nominal.fits|link=HFI_SkyMap_545_2048_R1.10_nominal.fits}}
 +
|-
 +
| '''857GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_nominal.fits|link=HFI_SkyMap_857_2048_R1.10_nominal.fits}}
 +
|- bgcolor="ffdead"
 +
! Frequency ||  Full channel, Zodi-corrected maps
 +
|-
 +
| '''100GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_nominal_ZodiCorrected.fits|link=HFI_SkyMap_100_2048_R1.10_nominal_ZodiCorrected.fits}}
 +
|-
 +
| '''143GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_nominal_ZodiCorrected.fits|link=HFI_SkyMap_143_2048_R1.10_nominal_ZodiCorrected.fits}}
 +
|-
 +
| '''217GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_nominal_ZodiCorrected.fits|link=HFI_SkyMap_217_2048_R1.10_nominal_ZodiCorrected.fits}}
 +
|-
 +
| '''353GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_nominal_ZodiCorrected.fits|link=HFI_SkyMap_353_2048_R1.10_nominal_ZodiCorrected.fits}}
 
|-
 
|-
| '''143–ds1:''' 143-1a,143-1b,143-3a,143-3b || '''143–ds2:''' 143-2a,143-2b,143-4a,143-4b
+
| '''545GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_nominal_ZodiCorrected.fits|link=HFI_SkyMap_545_2048_R1.10_nominal_ZodiCorrected.fits}}
 
|-
 
|-
| '''217–ds1:''' 217-5a,217-5b,217-7a,217-7b || '''217–ds2:''' 217-6a,217-6b,217-8a,217-8b
+
| '''857GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_nominal_ZodiCorrected.fits|link=HFI_SkyMap_857_2048_R1.10_nominal_ZodiCorrected.fits}}
 +
|- bgcolor="ffdead"
 +
! Frequency || Combined frequency maps
 
|-
 
|-
| '''353–ds1:''' 353-5a,353-5b,353-3a,353-3b || '''353–ds2:''' 353-6a,353-6b,353-4a,353-4b
+
| '''All''' || {{PLASingleFile|fileType=file|name=COM_MapSet_I-allFreqs_R1.10_nominal.fits|link=COM_MapSet_I-allFreqs_R1.10_nominal.fits}}
 
|}
 
|}
  
The LFI Detector-set maps are built using pairs of horns in the same scanning row, namely:
 
  
{| class="wikitable"  align="center" style="text-align:center" border="1" cellpadding="5" cellspacing="0"  
+
{| class="wikitable"  align="center" style="text-align:center" border="1" cellpadding="5" cellspacing="0" width=850px
|+ '''LFI Couple Horn sets'''
+
|+ '''FITS filenames'''
| '''18_23:''' 18M,18S,23M,23S
+
|- bgcolor="ffdead"
 +
! Frequency ||  Survey 1 maps || Survey 2 maps
 +
|-
 +
| '''30GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_030_1024_R1.10_survey_1.fits|link=LFI_SkyMap_030_1024_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_030_1024_R1.10_survey_2.fits|link=LFI_SkyMap_030_1024_R1.10_survey_2.fits}}
 +
|-
 +
| '''44GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_044_1024_R1.10_survey_1.fits|link=LFI_SkyMap_044_1024_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_044_1024_R1.10_survey_2.fits|link=LFI_SkyMap_044_1024_R1.10_survey_2.fits}}
 +
|-
 +
| '''70GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_070_1024_R1.10_survey_1.fits|link=LFI_SkyMap_070_1024_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_070_1024_R1.10_survey_2.fits|link=LFI_SkyMap_070_1024_R1.10_survey_2.fits}}
 +
|-
 +
| '''70GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_070_2048_R1.10_survey_1.fits|link=LFI_SkyMap_070_2048_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_070_2048_R1.10_survey_2.fits|link=LFI_SkyMap_070_2048_R1.10_survey_2.fits}}
 +
|-
 +
| '''100GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_survey_1.fits|link=HFI_SkyMap_100_2048_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_survey_2.fits|link=HFI_SkyMap_100_2048_R1.10_survey_2.fits}}
 +
|-
 +
| '''143GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_survey_1.fits|link=HFI_SkyMap_143_2048_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_survey_2.fits|link=HFI_SkyMap_143_2048_R1.10_survey_2.fits}}
 +
|-
 +
| '''217GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_survey_1.fits|link=HFI_SkyMap_217_2048_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_survey_2.fits|link=HFI_SkyMap_217_2048_R1.10_survey_2.fits}}
 +
|-
 +
| '''353GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_survey_1.fits|link=HFI_SkyMap_353_2048_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_survey_2.fits|link=HFI_SkyMap_353_2048_R1.10_survey_2.fits}}
 +
|-
 +
| '''545GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_survey_1.fits|link=HFI_SkyMap_545_2048_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_survey_2.fits|link=HFI_SkyMap_545_2048_R1.10_survey_2.fits}}
 +
|-
 +
| '''857GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_survey_1.fits|link=HFI_SkyMap_857_2048_R1.10_survey_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_survey_2.fits|link=HFI_SkyMap_857_2048_R1.10_survey_2.fits}}
 +
|- bgcolor="ffdead"
 +
! Frequency ||  Survey 1 Zodi-corrected maps || Survey 2 Zodi-corrected maps
 +
|-
 +
| '''100GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_survey_1_ZodiCorrected.fits|link=HFI_SkyMap_100_2048_R1.10_survey_1_ZodiCorrected.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_survey_2_ZodiCorrected.fits|link=HFI_SkyMap_100_2048_R1.10_survey_2_ZodiCorrected.fits}}
 +
|-
 +
| '''143GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_survey_1_ZodiCorrected.fits|link=HFI_SkyMap_143_2048_R1.10_survey_1_ZodiCorrected.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_survey_2_ZodiCorrected.fits|link=HFI_SkyMap_143_2048_R1.10_survey_2_ZodiCorrected.fits}}
 +
|-
 +
| '''217GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_survey_1_ZodiCorrected.fits|link=HFI_SkyMap_217_2048_R1.10_survey_1_ZodiCorrected.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_survey_2_ZodiCorrected.fits|link=HFI_SkyMap_217_2048_R1.10_survey_2_ZodiCorrected.fits}}
 +
|-
 +
| '''353GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_survey_1_ZodiCorrected.fits|link=HFI_SkyMap_353_2048_R1.10_survey_1_ZodiCorrected.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_survey_2_ZodiCorrected.fits|link=HFI_SkyMap_353_2048_R1.10_survey_2_ZodiCorrected.fits}}
 +
|-
 +
| '''545GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_survey_1_ZodiCorrected.fits|link=HFI_SkyMap_545_2048_R1.10_survey_1_ZodiCorrected.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_survey_2_ZodiCorrected.fits|link=HFI_SkyMap_545_2048_R1.10_survey_2_ZodiCorrected.fits}}
 +
|-
 +
| '''857GHz''' || {{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_survey_1_ZodiCorrected.fits|link=HFI_SkyMap_857_2048_R1.10_survey_1_ZodiCorrected.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_survey_2_ZodiCorrected.fits|link=HFI_SkyMap_857_2048_R1.10_survey_2_ZodiCorrected.fits}}
 +
|- bgcolor="ffdead"
 +
! Frequency ||  Half-ring 1 maps ||Half-ring 2 maps
 +
|-
 +
| '''30GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_030_1024_R1.10_nominal_ringhalf_1.fits|link=LFI_SkyMap_030_1024_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_030_1024_R1.10_nominal_ringhalf_2.fits|link=LFI_SkyMap_030_1024_R1.10_nominal_ringhalf_2.fits}}
 +
|-
 +
| '''44GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_044_1024_R1.10_nominal_ringhalf_1.fits|link=LFI_SkyMap_044_1024_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_044_1024_R1.10_nominal_ringhalf_2.fits|link=LFI_SkyMap_044_1024_R1.10_nominal_ringhalf_2.fits}}
 +
|-
 +
| '''70GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_070_1024_R1.10_nominal_ringhalf_1.fits|link=LFI_SkyMap_070_1024_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_070_1024_R1.10_nominal_ringhalf_2.fits|link=LFI_SkyMap_070_1024_R1.10_nominal_ringhalf_2.fits}}
 +
|-
 +
| '''70GHz''' || {{PLASingleFile|fileType=map|name=LFI_SkyMap_070_2048_R1.10_nominal_ringhalf_1.fits|link=LFI_SkyMap_070_2048_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=LFI_SkyMap_070_2048_R1.10_nominal_ringhalf_2.fits|link=LFI_SkyMap_070_2048_R1.10_nominal_ringhalf_2.fits}}
 +
|-
 +
| '''100GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_nominal_ringhalf_1.fits|link=HFI_SkyMap_100_2048_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_100_2048_R1.10_nominal_ringhalf_2.fits|link=HFI_SkyMap_100_2048_R1.10_nominal_ringhalf_2.fits}}
 +
|-
 +
| '''143GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_nominal_ringhalf_1.fits|link=HFI_SkyMap_143_2048_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_143_2048_R1.10_nominal_ringhalf_2.fits|link=HFI_SkyMap_143_2048_R1.10_nominal_ringhalf_2.fits}}
 
|-
 
|-
| '''19_22:''' 19M,19S,22M,22S
+
| '''217GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_nominal_ringhalf_1.fits|link=HFI_SkyMap_217_2048_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_217_2048_R1.10_nominal_ringhalf_2.fits|link=HFI_SkyMap_217_2048_R1.10_nominal_ringhalf_2.fits}}
 
|-
 
|-
| '''20_21:''' 20M,20S,21M,21S
+
| '''353GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_nominal_ringhalf_1.fits|link=HFI_SkyMap_353_2048_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_353_2048_R1.10_nominal_ringhalf_2.fits|link=HFI_SkyMap_353_2048_R1.10_nominal_ringhalf_2.fits}}
 
|-
 
|-
| '''24:''' 24M,24S
+
| '''545GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_nominal_ringhalf_1.fits|link=HFI_SkyMap_545_2048_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_545_2048_R1.10_nominal_ringhalf_2.fits|link=HFI_SkyMap_545_2048_R1.10_nominal_ringhalf_2.fits}}
 
|-
 
|-
| '''25_26:''' 25M,25S,26M,26S
+
| '''857GHz''' ||  {{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_nominal_ringhalf_1.fits|link=HFI_SkyMap_857_2048_R1.10_nominal_ringhalf_1.fits}} ||
 +
{{PLASingleFile|fileType=map|name=HFI_SkyMap_857_2048_R1.10_nominal_ringhalf_2.fits|link=HFI_SkyMap_857_2048_R1.10_nominal_ringhalf_2.fits}}
 
|}
 
|}
  
-->
+
== FITS file structure ==
  
== List of products ==
 
  
The list of products containing sky maps are given below, grouped by type
+
[[File:FITS_FreqMap.png | 500px  | right | thumb | '''FITS file structure''']]
  
<span style="color:red">Outstanding: link to archive objects / LFI to fill in their products</span>
+
The FITS files for the sky maps contain a minimal primary header with no data, and a ''BINTABLE'' extension (EXTENSION 1, EXTNAME = ''FREQ-MAP'') containing the data.  The structure is shows schematically in the figure at right. 
  
; Full channel maps :
+
The ''FREQ-MAP'' extension contains is a 3-column table that contain the signal, hit-count and variance maps, all in Healpix format, in columns 1, 2, and 3, respectively. The number of rows is 50331648 for HFI and LFI 70 GHz at Nside=2048 and 12582912 for LFI maps at Nside=1024 (N.B: Npix = 12 Nside^2)The three columns are ''I_STOKES'' for the intensity (or temperature) signal, ''HIT'' for the hit-count and ''II_COV'' for the varianceThe exact order of the columns in the figure is indicative only, and the details can be found in the keywords.   
  LFI maps .
 
HFI_SkyMap_100_2048_R1.nn_nominal.fits
 
  HFI_SkyMap_143_2048_R1.nn_nominal.fits
 
  HFI_SkyMap_217_2048_R1.nn_nominal.fits
 
  HFI_SkyMap_353_2048_R1.nn_nominal.fits
 
  HFI_SkyMap_545_2048_R1.nn_nominal.fits
 
HFI_SkyMap_857_2048_R1.nn_nominal.fits
 
  
; Single survey maps :
+
Keywords indicate the coordinate system (GALACTIC), the Healpix ordering scheme (NESTED), the units (K_cmb or MJy/sr) of each column, and of course the frequency channel (FREQ). The COMMENT fields give a one-line summary of the product, and some other information useful for traceability within the DPCs. The original filename is also given in the ''FILENAME'' keyword as are the datasum and the md5 checksum for the extension. The ''BAD_DATA'' keyword gives the value used by Healpix to indicate pixels for which no signal is present (these will also have a hit-count value of 0)The COMMENT fields give further information including some traceability data for the DPC'sThe main parameters are summarised below:
LFI maps ….
 
HFI_SkyMap_100_2048_R1.nn_survey_1.fits
 
HFI_SkyMap_143_2048_R1.nn_survey_1.fits
 
  HFI_SkyMap_217_2048_R1.nn_survey_1.fits
 
  HFI_SkyMap_353_2048_R1.nn_survey_1.fits
 
HFI_SkyMap_545_2048_R1.nn_survey_1.fits
 
HFI_SkyMap_857_2048_R1.nn_survey_1.fits
 
HFI_SkyMap_100_2048_R1.nn_survey_2.fits
 
HFI_SkyMap_143_2048_R1.nn_survey_2.fits
 
HFI_SkyMap_217_2048_R1.nn_survey_2.fits
 
HFI_SkyMap_353_2048_R1.nn_survey_2.fits
 
HFI_SkyMap_545_2048_R1.nn_survey_2.fits
 
HFI_SkyMap_857_2048_R1.nn_survey_2.fits
 
  
  
; Half-ring maps :
+
{| border="1" cellpadding="3" cellspacing="0" align="center" style="text-align:left" width=800px
LFI maps ….
+
|+ '''Sky map file data structure'''
HFI_SkyMap_100_2048_R1.nn_nominal_ringhalf_1.fits
+
|- bgcolor="ffdead" 
HFI_SkyMap_143_2048_R1.nn_nominal_ringhalf_1.fits
+
!colspan="4" | 1. EXTNAME = 'FREQ-MAP' : Data columns
HFI_SkyMap_217_2048_R1.nn_nominal_ringhalf_1.fits
+
|- bgcolor="ffdead" 
HFI_SkyMap_353_2048_R1.nn_nominal_ringhalf_1.fits
+
! Column Name || Data Type || Units || Description
HFI_SkyMap_545_2048_R1.nn_nominal_ringhalf_1.fits
+
|-
HFI_SkyMap_857_2048_R1.nn_nominal_ringhalf_1.fits
+
|I_STOKES || Real*4 || K_cmb or MJy/sr || The signal map
HFI_SkyMap_100_2048_R1.nn_nominal_ringhalf_2.fits
+
|-
HFI_SkyMap_143_2048_R1.nn_nominal_ringhalf_2.fits
+
|HITS || Int*4 || none || The hit-count map
HFI_SkyMap_217_2048_R1.nn_nominal_ringhalf_2.fits
+
|-
HFI_SkyMap_353_2048_R1.nn_nominal_ringhalf_2.fits
+
|II_COV || Real*4 || K_cmb<sup>2</sup> or (MJy/sr)<sup>2</sup> || The variance map
HFI_SkyMap_545_2048_R1.nn_nominal_ringhalf_2.fits
+
|- bgcolor="ffdead" 
HFI_SkyMap_857_2048_R1.nn_nominal_ringhalf_2.fits
+
! Keyword || Data Type || Value || Description
 
+
|-
; Zodi and Far-side-lobes corrected maps :
+
|PIXTYPE || string || HEALPIX ||
  HFI_SkyMap_100_2048_R1.nn_nominal_ZodiCorrected.fits
+
|-
HFI_SkyMap_143_2048_R1.nn_nominal_ZodiCorrected.fits
+
|COORDSYS || string || GALACTIC ||Coordinate system
  HFI_SkyMap_217_2048_R1.nn_nominal_ZodiCorrected.fits
+
|-
HFI_SkyMap_353_2048_R1.nn_nominal_ZodiCorrected.fits
+
|ORDERING || string || NESTED || Healpix ordering
HFI_SkyMap_545_2048_R1.nn_nominal_ZodiCorrected.fits
+
|-
  HFI_SkyMap_857_2048_R1.nn_nominal_ZodiCorrected.fits
+
|NSIDE ||  Int || 1024 or 2048 || Healpix Nside
 
+
|-
  HFI_SkyMap_100_2048_R1.nn_survey_1_ZodiCorrected.fits
+
|FIRSTPIX ||  Int*4 ||                  0 || First pixel number
HFI_SkyMap_143_2048_R1.nn_survey_1_ZodiCorrected.fits
+
|-
HFI_SkyMap_217_2048_R1.nn_survey_1_ZodiCorrected.fits
+
|LASTPIX ||  Int*4 || 12582911 or 50331647 || Last pixel number
HFI_SkyMap_353_2048_R1.nn_survey_1_ZodiCorrected.fits
+
|-
HFI_SkyMap_545_2048_R1.nn_survey_1_ZodiCorrected.fits
+
|FREQ ||    string ||                nnn || The frequency channel  
HFI_SkyMap_857_2048_R1.nn_survey_1_ZodiCorrected.fits
+
|}
HFI_SkyMap_100_2048_R1.nn_survey_2_ZodiCorrected.fits
 
  HFI_SkyMap_143_2048_R1.nn_survey_2_ZodiCorrected.fits
 
HFI_SkyMap_217_2048_R1.nn_survey_2_ZodiCorrected.fits
 
HFI_SkyMap_353_2048_R1.nn_survey_2_ZodiCorrected.fits
 
HFI_SkyMap_545_2048_R1.nn_survey_2_ZodiCorrected.fits
 
HFI_SkyMap_857_2048_R1.nn_survey_2_ZodiCorrected.fits
 
  
  
---- '''A comment from E. Keihänen: '''
+
The same structure applies to all ''SkyMap'' products, independent of whether they are full channel, survey of half-ring. The distinction between the types of maps is present in the FITS filename (and in the traceability comment fields).
 
 
Here is a list of things that should go into this section:
 
Insert a table of maps delivered:
 
*file name
 
*radiometers included
 
*PID/OD range
 
*resolution
 
*(-polarization included or not)
 
*sky coverage
 
*baseline length
 
*-reference to input toi objects)
 
  Explain the format of the files, what is in what column, in what units.
 
Information common for all LFImaps:
 
*LFI maps were constructed with the Madam map-making code (version 3.7.4).
 
Maps are in Healpix format, in nested pixeling scheme, in K_cmb units, and in galactic coordinate system.
 
*Unobserved pixels are marked by the special value -1.6375e30.
 
 
 
EK's comment ends ------
 
 
 
 
 
 
 
== FITS file structure ==
 
 
 
[[File:FITS_FreqMap.png | 500px  | right | thumb | '''FITS file structure''']]
 
  
The FITS files for the sky maps contain a simple primary header with no data, and ''BINTABLE'' extension (EXTENSION 1, EXTNAME = 'FREQ-MAP') containing the data.  The structure is shows schematically in the figure at right.  The primary header has the form
+
== References ==
  
;-----------------------------------------------------------------------------
 
; EXTENSION 0:
 
; - Header
 
;-----------------------------------------------------------------------------
 
MRDFITS: Null image, NAXIS=0
 
SIMPLE  =                    T /Dummy Created by MWRFITS v1.11                 
 
BITPIX  =                    8 /Dummy primary header created by MWRFITS       
 
NAXIS  =                    0 /No data is associated with this header         
 
EXTEND  =                    T /Extensions may (will!) be present             
 
END                                                                           
 
 
 
The ''FREQ-MAP'' BINTABLE extension contains the data.  The table contains 3 columns of that contain the signal, variance, and hit-count maps in Healpix format.  the number of rows is 50331648 for HFI and 12582912 for LFI, corresponding to the number of pixels in a Healpix map of Nside= 2048 and 1024, respectively (N.B: Npix = 12 Nside^2).  The 3 columns are ''I_STOKES'' for the intensity (or temperature) signal, ''II_COV'' for the variance, and ''HIT'' for the hit-count. 
 
The exact order of the columns in the figure is indicative only, and the details can be found in the keywords.  Keywords also indicate the coordinate system (GALACTIC), the Healpix ordering scheme (NESTED), the units (K_cmb or MJy/sr) of each column, and of course the frequency channel (FREQ). The COMMENT fields give a one-line summary of the product, and some other information useful for traceability within the DPCs. The original filename is also given in the ''FILENAME'' keyword as is the md5 checksum for the extension. The ''BAD_DATA'' keyword gives the value used by Healpix to indicate pixels for which no signal is present (these will also have a hit-count value of 0).
 
  
A typical header for the data extension of an intensity only map is:
+
<References />
  
;-----------------------------------------------------------------------------
 
; EXTENSION 1: FREQ-MAP
 
; - Header
 
;-----------------------------------------------------------------------------
 
MRDFITS: Binary table.  3 columns by  1 rows.
 
XTENSION= 'BINTABLE'          /Written by IDL:  Thu Jan 31 11:03:21 2013     
 
BITPIX  =                    8 /                                               
 
NAXIS  =                    2 /Binary table                                   
 
NAXIS1  =            603979776 /Number of bytes per row                       
 
NAXIS2  =                    1 /Number of rows                                 
 
PCOUNT  =                    0 /Random parameter count                         
 
GCOUNT  =                    1 /Group count                                   
 
TFIELDS =                    3 /Number of columns                             
 
COMMENT                                                                       
 
COMMENT  *** End of mandatory fields ***                                       
 
COMMENT                                                                       
 
EXTVER  =                    1 /Extension version                             
 
DATE    = '2013-01-31'        /Creation date                                 
 
COMMENT                                                                       
 
COMMENT  *** Column names ***                                                 
 
COMMENT                                                                       
 
TTYPE1  = 'I_STOKES'          /                                               
 
TTYPE2  = 'HITS    '          /                                               
 
TTYPE3  = 'II_COV  '          /                                               
 
COMMENT                                                                       
 
COMMENT  *** Column formats ***                                               
 
COMMENT                                                                       
 
TFORM1  = '50331648E'          /                                               
 
TFORM2  = '50331648J'          /                                               
 
TFORM3  = '50331648E'          /                                               
 
COMMENT                                                                       
 
COMMENT  *** Column units ***                                                 
 
COMMENT                                                                       
 
TUNIT1  = 'K_CMB  '          /                                               
 
TUNIT2  = '        '          /                                               
 
TUNIT3  = 'K_CMB^2'          /                                               
 
COMMENT                                                                       
 
COMMENT  *** Planck params ***                                                 
 
COMMENT                                                                       
 
EXTNAME = 'FREQ-MAP'          / Extension name                               
 
COORSYS = 'GALACTIC'          / Coordinate system                             
 
ORDERING= 'NESTED  '          / Healpix ordering                             
 
NSIDE  =                2048 / Healpix Nside                                 
 
FIRSTPIX=                    0 / First pixel # (0 based)                       
 
LASTPIX =            50331647 / Last pixel # (0 based)                       
 
FILENAME= 'HFI_SkyMap_217_2048_R1.10_nominal_ZodiCorrected.fits' / FITS filename
 
CHECKSUM= '3aIB6Z993aGA3Y99'  / HDU checksum created 2013-01-31T10:03:22     
 
BAD_DATA=        -1.63750E+30 / bad pixel value                               
 
FREQ    = '217    '          / reference frequency                           
 
PROCVER = 'DX9_Delta'          / Product version                               
 
COMMENT                                                                       
 
COMMENT ------------------------------------------------------------------------
 
COMMENT Full channel sky map: nominal mission, corrected for Zodi & FSL       
 
COMMENT ------------------------------------------------------------------------
 
COMMENT Link to description in Planck Explanatory Supplement:                 
 
COMMENT http://www.sciops.esa.int/wikiSI/planckpla/index.php?title=           
 
COMMENT Frequency_Maps&instance=Planck_PLA_ES                                 
 
COMMENT ------------------------------------------------------------------------
 
COMMENT HFI-DMC objects:                                                       
 
COMMENT in-group: MAP_v53_noZodi_2048_GALACTIC_0240_27008/                     
 
COMMENT Creation date  - object name                                           
 
COMMENT 13-01-03 18:33 - 217GHz_W_TauDeconv_nominal_I                         
 
COMMENT 13-01-03 18:33 - 217GHz_W_TauDeconv_nominal_H                         
 
COMMENT 13-01-03 18:33 - 217GHz_W_TauDeconv_nominal_II                         
 
COMMENT ------------------------------------------------------------------------
 
END                                                                           
 
  
The same structure applies to all ''SkyMap'' products, independent of whether they are full channel, survey of half-ring.  The distinction between the types of maps is present in the FITS filename (and in the traceability comment fields). 
 
  
  
[[Category:Mission science products]]
+
[[Category:Mission products|002]]

Latest revision as of 13:00, 24 July 2014

General description[edit]

Sky maps give the best estimate of the intensity of the signal from the sky after removal, as far as possible, of known systematic effects and of the dipole signals induced by the motion of the solar system in the CMB and of the Planck satellite in the solar system. Sky maps are provided for the nominal Planck mission and also, separately, for the first two single surveys, the third one being covered only for a small part during the nominal mission.The details of the start and end times of each are given in this table. As a secondary product, maps with estimates of the Zodiacal light and Far-Side-Lobes contribution removed are also provided.

For characterization purposes, are also provided maps covering the nominal survey but each one using only half of the available data. These are the ringhalf_{1|2} maps, which are built using the first and second half of the stable pointing part in each pointing period. These maps are used extensively to investigate the (high frequency) noise properties the maps themselves and of other products described elsewhere (see e.g., the data validation section).

To help in further processing, there are also masks of the Galactic Plane and of point sources, each provided for several different depths.

All sky maps are in Healpix format, with Nside of 2048 for HFI and of 1024 for LFI (note that the LFI 70 GHz has been delivered also at Nside of 2048 to be directly comparable with HFI maps), in Galactic coordinates, and Nested ordering. The signal is given in units of Kcmb for 30-353 GHz, and of MJy/sr (for a constant $\nu F_\nu$ energy distribution ) for 545 and 857 GHz. Each sky map is packaged into a BINTABLE extension of a FITS file together with a hit-count map (or hit map, for short, giving the number of observation samples that are cumulated in a pixel, all detectors combined) and a variance map (determined from the half-ring maps), and additional information is given in the FITS file header. The structure of the FITS file is given in the FITS file structure section below.

Types of maps[edit]

Full channel maps
Full channel maps are built using all the valid detectors of a frequency channel and cover the nominal mission. For HFI, the 143-8 and 545-3 bolometers are rejected entirely as they are seriously affected by RTS noise. The maps are displayed in the figures below. The range is the same from 30 - 143 GHz in order to show the CMB at the same level. At higher frequencies the range is increased in order to keep the Galactic Plane from invading the whole sky.
Single survey maps
Single survey maps are built using all valid detectors of a frequency channel; they cover separately the different sky surveys. The surveys are defined as the times over which the satellite spin axis rotates but 180 degrees, which, due to the position of the detectors in the focal plane does not cover the full sky, but a fraction between ~80 and 90% depending on detector position.
Detector set or detector pairs maps
These are maps built from a subset of the detectors in a frequency channel, typically our of two PSB pairs (i.e., four poloarisation-sensitive bolometers with different orientation on the sky), for HFI in order to extract a single temperature map. While none of these maps are part of the first Planck data release, the concept of detset is used, and thus it is worth mentioning it here. In particular, information by detector set is available at the sky power spectrum level and in the RIMO.
Half-ring maps
Half-ring maps are built using only the first or the second half of the stable pointing period data. There are thus two half-ring maps per frequency channel named ringhalf_1 and ringhalf_2 respectively. These maps are built for characterization purposes in order to perform null tests. In particular, the difference between the two half-ring maps at a given frequency give a good estimate of the high frequency noise in the data (albeit biased low by ~0.5% for the HFI channels due to specifics of the TOI processing).
Masks
Masks are provided of the Galactic Plane and of the point sources. For the Galactic Plane, eight masks are given covering different fractions of the sky, and for the points sources two masks are given, at the 5 and 10 sigma level, for each Planck HFI frequency channel. These are generic masks, specific masks applicable to other products are delivered with the products themselves.

Caveats and known issues[edit]

The primary limitation of the HFI maps are

  • the absence of correction of the ADC non-linearities,
  • the far-side lobe contribution is not accounted for in the processing and in the calibration,
  • the dipole removal is based on the non-relativistic approximation which leaves a weak quadrupole component in the map.

And thus the overall calibration accuracy is at the 0.2% level in 100-217 GHz channels

The LFI 70 GHz maps at Nside=2048 should be considered as additional product, the default are the LFI maps at Nside=1024. No effective beam at Nside=2048 is provided, only at Nside=1024, for this reason the use of the effective beam with maps at Nside 2048 is discouraged.

Map zero-level[edit]

For the 100 to 857 GHz maps, the zero levels are set to their optimal levels for Galactic and CIB studies. A procedure for adjusting them to astrophysical values is given in the HFI Calibration paper Planck-2013-VIII[1].

For the 30, 44 and 70 GHz, maps are corrected for zero level monopole by applying an offset correction, see LFI Calibration paper Planck-2013-V[2] section 3.4 "Setting the zero levels in the maps". Note that the offset applied is indicated in the header as a comment keyword.

The Zodiacal light and the Far-Side Lobes[edit]

The figures below show the modeled Zodiacal light and Far Side Lobes projected onto the maps; they are simply the difference between the main product and the ZodiCorrected maps for the nominal mission. The units are given in the figures. The heat color table has been used in place of the standard Planck for clarity reasons.

The effects of the FSLs are seen most clearly at the highest frequencies, as structures roughly symmetric about the center of the image, which corresponds to the location of the Galactic Centre, which is in turn the source of most of the radiation that is scattered into the FSLs.

Artifacts near caustics of the scanning strategy[edit]

The scanning strategy is such that regions around the Ecliptic poles are surveyed very deeply and compared to the average, and the transition from the nominal depth to the high depth, as shows on hit-count maps is very rapid, namely a few pixels, for a contrast of ~30. These transitions, or caustics in the maps, occur at different positions on the sky for different detectors, as the positions depend on their location in the focal plane of the instrument. As a result, when data from different detectors are combined to build a full channel map, the the weights of different detectors in the mix changes rapidly across the caustic, and given the remaining errors in the relative calibration of the detectors, a visible effect can be introduced in the maps, especially when the SNR is very high, i.e. at the highest frequencies and near bright regions like the Galactic Plane. Some examples are shown below.

Production process[edit]

Sky maps are produced by combining appropriately the data of all working detectors in a frequency channel over some period of the mission. They give the best estimate of the signal from the sky (unpolarised) after removal, as far as possible, of known systematic effects and of the dipole signals induced by the motion of the solar system in the CMB and of the Planck satellite in the solar system. In particular, they include the Zodiacal light emission (Zodi for short) and also the scattering from the far-side lobes of the beams (FSL). More on this below.

HFI processing[edit]

The inputs to the mapmaking are TOIs of signal that have been cleaned (as far as possible) of instrumental effects and calibrated in absorbed watts. While the processing involved is described in detail in the TOI processing section, we give a very brief summary here for convenience. That pipeline performs the following operations:

demodulation
this is performed around a variable level which is determined from the valid input data (a validity flag from a previous version of the processing is used for this purpose), and the data are converted to engineering units (V) using known conversion coefficients.
despiking
using the demodulated data converted to V (by the transfer function) the glitches are identified and fitted with templates. A glitch flag is produced that identifies the strongest part of the glitches, and a timeline of glitch tails is produced from the template fits, and subtracted from the demodulated timeline from step 1. Finally, the flagged ranges are replaced with data from an average over the pointing period (TBC)
dark template removal
the two dark bolometers are demodulated and despiked as above; the resulting timelines are then smoothed and used as an indicator of the overall temperature variations of the bolometer plate. Where the variations are consistent with each other, they are combined and removed from the bolometer signal timelines using appropriate coupling coefficients. The few percent of the data where they are not consistent are flagged on the timelines.
conversion to absorbed power
the timeline is converted to watts of absorbed power using the bolometer function. This includes a non-linearity correction; removal of the 4K cooler lines: the electromagnetic interference of the 4K cooler with the bolometer readout wires induces some sharp lines in the signal power spectra at frequencies of the 4K cooler's fundamental and its multiples, folded by the signal modulations. Fourier coefficients of the relevant lines are determined on a per-ring basis, and then removed from the data. The quality of the removal depends on the bolometer.
deconvolution by the time transfer function
this is done to correct for the non-instantaneous time response of the bolometers. The function itself is modeled using 4 parameters which are adjusted primarily on the planet data and also from comparisons of the northward and southward scans of the Galactic Plane. It is then removed using Fourier techniques, which has the side-effect of increasing the noise at high frequencies.
jump correction
removes some (relatively rare: 0.3 jumps per bolometer per pointing period, on average) jumps in the signal baseline. The jumps are detected characterized on smoothed TOIs, and corrected by adding a constant to part of the signal timeline. The origin of the jumps is not known.

The results of this processing are a timeline of signal (in absorbed watts) and a valid data flag timeline for each of the 50 valid bolometers processed; these timelines contain the full sky signal, i.e., including the solar and orbital dipoles, the Zodiacal light, and contributions from the Far-Side lobes. The dipoles are necessary for the flux calibration and are removed at the mapmaking stage. The remaining two bolometers (143-8 and 535-3) show semi-random jumps in the signal level, typically jumping over 2-5 different pseudo-baseline levels, a behavior known as Random Telegraphic Signal, so that these are commonly called the RTS bolometers. Finally, ring-level statistics of different types (mean, median, rms, kurtosis, etc.) are determined on a per-ring basis for all timelines, and a selection based on these statistics is used to discard anomalous rings, which are recorded in a ring-level flag for each valid bolometer timeline (see the Discarded rings section).

Throughout this processing, bright planets (Mars, Jupiter, Saturn, Uranus) and bright asteroids are masked in the timeline in order to avoid ringing effects in the processing. Since they move on the sky, the portion of the sky masked during one survey is observed during one, and no hole is left in the final map. In parallel, the planet data are processed in a similar way, but with different parameters for the despiking step, and without the final jump correction step. These results are processed separately to determine the beam shapes and the focal plane geometry.

The pointing is determined starting from the AHF produced by MOC, which gives the direction and orientation of the LOS of a fiducial position in the focal plane at frequencies of 8Hz during stable pointing and 4 Hz during maneuvers (TBC for details, reference). This is interpolated to the times of data observation (ref to method), corrected for the wobble and other time-dependent offsets determined from the observed positions of a large number of sources around the sky, and finally converted to the LOS of each detector using the quaternions in the IMO (which are determined from observations of bright planets - see the Detector_pointing section).

The mapmaking and calibration process is described in detail in the Map-making section, where detailed references are found. In brief it consists of:

binning the TOI data onto rings 
Healpix rings (HPRs) are used here, each ring containing the combined data of one pointing period.
flux calibration 
at 100-353 GHz, the flux calibration factors are determined for each pointing period (or ring) from the solar-motion dipole, using the WMAP dipole as the reference, and after removal of the dipole signal induced by the motion of the Planck satellite in the solar system. This gain by ring is smoothed with a window of width 50 rings, which reveals an apparent variation of ~1-2% on a scale of 100s to 1000s of rings for the 100-217 GHz channels, and is applied. At 353GHz, where the solar motion dipole is weaker compared to the signal, no gain variation is detected (within the uncertainties), and a single fixed gain is applied to all rings. At 545 and 857 GHz the gain is determined from the observation of Uranus and Neptune (but not Jupiter which is too bright) and comparison to recent models made explicitly for this mission. A single gain is applied to all rings at these frequencies.
destriping 
in order to remove low-frequency noise, an offset per ring is determined by minimizing the differences between HPRs at their crossings, and removed.
projection onto the map 
the offset-corrected and flux-calibrated HPRs are projected onto Healpix maps, with the data of each bolometer weighted by a factor of 1/NET of that bolometer, and accounting for the slight different band transmission profiles of the bolometers in each band.

These maps provide the main mission products. A second, reduced, set of maps, cleaned of the Zodiacal emission of the FSL leakage is also produced for the nominal mission and the two single surveys, but not for the half-rings (since the contribution would be the same for the two halves of each ring). For this purpose, the the Zodiacal emission and the FSL contamination, which are not fixed on the sky, are modeled separately at HPR-level, and subtracted from the signal HPR before projecting them onto the maps.

Together with signal maps, hit count and variance maps are also produced. The hit maps give the (integer) number of valid TOI-level samples that contribute to the signal of each pixel. All valid samples are counted in the same way, i.e., there is no weighting factor applied. The variance maps project the white noise estimate, provided by the NETs, in the sky domain.

LFI processing[edit]

LFI maps were constructed with the Madam map-making code, version 3.7.4. The code is based on generalized destriping technique, where the correlated noise component is modeled as a sequence of constant offset, called baselines. A noise filter was used to constrain the baseline solution allowing the use of 1 second baselines.

Radiometers were combined according to the horn-uniform weighting scheme to minimize systematics. The used weights are listed in Map-making. The flagged samples were excluded from the analysis by setting their weights to $C_{w}^{-1}$ = 0. The galaxy region was masked out in the destriping phase, to reduce error arising from strong signal gradients. The polarization component was included in the analysis, although only the temperature maps are released.

A detailed description of the map-making procedure is given in Planck-2013-II[3] and in section Map-making.

Inputs[edit]

HFI inputs[edit]

  • The cleaned TOIs of signal of each detector, together with their flags, produced by the TOI processing pipeline
  • The TOIs of pointing (quaternions), described in Detector_pointing
  • Bolometer-level characterization data, from the DPC's internal IMO (not distributed)
  • Planck orbit data used to compute and remove the earth dipole
  • WMAP solar dipole information used to calibrate the CMB channels
  • Planet models used to calibrate the Galactic channels.

LFI inputs[edit]

The Madam map-maker takes as an input:

  • The calibrated timelines (for details see TOI Processing)
  • The detector pointings (for details see Detector pointing)
  • The noise information in the form of three-parameter (white noise level ($\sigma$), slope, and knee frequency ($f_\mathrm{knee}$)) noise model (for details see RIMO)

Related products[edit]

Masks[edit]

Masks are provided of

the point sources
15 masks are provided, three for the LFI (one mask for each frequency masking at the 4[math]\sigma[/math] level) and 12 for the HFI (two masks for each frequency at the 5 and 10[math]\sigma[/math] levels. For the HFI the masks can be used as they are, for the LFI they need to be downgraded to Nside=1024 except for the 70 GHz channel at Nside=2048 which does not need to be downgraded.
the Galactic Plane
8 masks are provided giving 20, 40, 60, 70, 80, 90, 97, and 99% sky coverage in two different files, at Nside=2048. For the HFI they can be used as they are, for the LFI they need to be downgraded at Nside=1024 (note that if using the 70 GHZ at Nside=2048 no downgraded is needed)


The masks are binary, in GALACTIC coordinates, and NESTED ordering. The table below give the filenames.


FITS filenames for masks
Frequency LFI Point Source masks
30GHz LFI_MASK_030-ps_2048_R1.00.fits
44GHz LFI_MASK_044-ps_2048_R1.00.fits
70GHz LFI_MASK_070-ps_2048_R1.00.fits
HFI Point Source masks
HFI_Mask_PointSrc_2048_R1.10.fits
Galactic Plane masks
HFI_Mask_GalPlane_2048_R1.10.fits


The masks are shows below in a single figure. While this is quite clear for the Galactic Plane masks, it is less so for the point source masks, but it does give a clear perspective on how the latter are distributed over the sky.

File names[edit]

The FITS filenames are of the form {H|L}FI_SkyMap_fff_nnnn_R1.nn_{coverage}_{type}.fits, where fff are three digits to indicate the Planck frequency band, and nnnn is the Healpix Nside of the map, coverage indicates which part of the mission is covered, and the optional type indicates the subset of input data used. A full list of products, with links to them in the Archive, is given in the tables below.

For the benefit of users who are only looking for the frequency maps with no additional information, we also provide a file combining the 9 frequency maps as separate columns in a single extension. The 9 columns in this file contain the intensity maps ONLY and no other information (hit maps and variance maps) is provided.

FITS filenames
Frequency Full channel maps
30GHz LFI_SkyMap_030_1024_R1.10_nominal.fits
44GHz LFI_SkyMap_044_1024_R1.10_nominal.fits
70GHz LFI_SkyMap_070_1024_R1.10_nominal.fits
70GHz LFI_SkyMap_070_2048_R1.10_nominal.fits
100GHz HFI_SkyMap_100_2048_R1.10_nominal.fits
143GHz HFI_SkyMap_143_2048_R1.10_nominal.fits
217GHz HFI_SkyMap_217_2048_R1.10_nominal.fits
353GHz HFI_SkyMap_353_2048_R1.10_nominal.fits
545GHz HFI_SkyMap_545_2048_R1.10_nominal.fits
857GHz HFI_SkyMap_857_2048_R1.10_nominal.fits
Frequency Full channel, Zodi-corrected maps
100GHz HFI_SkyMap_100_2048_R1.10_nominal_ZodiCorrected.fits
143GHz HFI_SkyMap_143_2048_R1.10_nominal_ZodiCorrected.fits
217GHz HFI_SkyMap_217_2048_R1.10_nominal_ZodiCorrected.fits
353GHz HFI_SkyMap_353_2048_R1.10_nominal_ZodiCorrected.fits
545GHz HFI_SkyMap_545_2048_R1.10_nominal_ZodiCorrected.fits
857GHz HFI_SkyMap_857_2048_R1.10_nominal_ZodiCorrected.fits
Frequency Combined frequency maps
All COM_MapSet_I-allFreqs_R1.10_nominal.fits


FITS filenames
Frequency Survey 1 maps Survey 2 maps
30GHz LFI_SkyMap_030_1024_R1.10_survey_1.fits

LFI_SkyMap_030_1024_R1.10_survey_2.fits

44GHz LFI_SkyMap_044_1024_R1.10_survey_1.fits

LFI_SkyMap_044_1024_R1.10_survey_2.fits

70GHz LFI_SkyMap_070_1024_R1.10_survey_1.fits

LFI_SkyMap_070_1024_R1.10_survey_2.fits

70GHz LFI_SkyMap_070_2048_R1.10_survey_1.fits

LFI_SkyMap_070_2048_R1.10_survey_2.fits

100GHz HFI_SkyMap_100_2048_R1.10_survey_1.fits

HFI_SkyMap_100_2048_R1.10_survey_2.fits

143GHz HFI_SkyMap_143_2048_R1.10_survey_1.fits

HFI_SkyMap_143_2048_R1.10_survey_2.fits

217GHz HFI_SkyMap_217_2048_R1.10_survey_1.fits

HFI_SkyMap_217_2048_R1.10_survey_2.fits

353GHz HFI_SkyMap_353_2048_R1.10_survey_1.fits

HFI_SkyMap_353_2048_R1.10_survey_2.fits

545GHz HFI_SkyMap_545_2048_R1.10_survey_1.fits

HFI_SkyMap_545_2048_R1.10_survey_2.fits

857GHz HFI_SkyMap_857_2048_R1.10_survey_1.fits

HFI_SkyMap_857_2048_R1.10_survey_2.fits

Frequency Survey 1 Zodi-corrected maps Survey 2 Zodi-corrected maps
100GHz HFI_SkyMap_100_2048_R1.10_survey_1_ZodiCorrected.fits

HFI_SkyMap_100_2048_R1.10_survey_2_ZodiCorrected.fits

143GHz HFI_SkyMap_143_2048_R1.10_survey_1_ZodiCorrected.fits

HFI_SkyMap_143_2048_R1.10_survey_2_ZodiCorrected.fits

217GHz HFI_SkyMap_217_2048_R1.10_survey_1_ZodiCorrected.fits

HFI_SkyMap_217_2048_R1.10_survey_2_ZodiCorrected.fits

353GHz HFI_SkyMap_353_2048_R1.10_survey_1_ZodiCorrected.fits

HFI_SkyMap_353_2048_R1.10_survey_2_ZodiCorrected.fits

545GHz HFI_SkyMap_545_2048_R1.10_survey_1_ZodiCorrected.fits

HFI_SkyMap_545_2048_R1.10_survey_2_ZodiCorrected.fits

857GHz HFI_SkyMap_857_2048_R1.10_survey_1_ZodiCorrected.fits

HFI_SkyMap_857_2048_R1.10_survey_2_ZodiCorrected.fits

Frequency Half-ring 1 maps Half-ring 2 maps
30GHz LFI_SkyMap_030_1024_R1.10_nominal_ringhalf_1.fits

LFI_SkyMap_030_1024_R1.10_nominal_ringhalf_2.fits

44GHz LFI_SkyMap_044_1024_R1.10_nominal_ringhalf_1.fits

LFI_SkyMap_044_1024_R1.10_nominal_ringhalf_2.fits

70GHz LFI_SkyMap_070_1024_R1.10_nominal_ringhalf_1.fits

LFI_SkyMap_070_1024_R1.10_nominal_ringhalf_2.fits

70GHz LFI_SkyMap_070_2048_R1.10_nominal_ringhalf_1.fits

LFI_SkyMap_070_2048_R1.10_nominal_ringhalf_2.fits

100GHz HFI_SkyMap_100_2048_R1.10_nominal_ringhalf_1.fits

HFI_SkyMap_100_2048_R1.10_nominal_ringhalf_2.fits

143GHz HFI_SkyMap_143_2048_R1.10_nominal_ringhalf_1.fits

HFI_SkyMap_143_2048_R1.10_nominal_ringhalf_2.fits

217GHz HFI_SkyMap_217_2048_R1.10_nominal_ringhalf_1.fits

HFI_SkyMap_217_2048_R1.10_nominal_ringhalf_2.fits

353GHz HFI_SkyMap_353_2048_R1.10_nominal_ringhalf_1.fits

HFI_SkyMap_353_2048_R1.10_nominal_ringhalf_2.fits

545GHz HFI_SkyMap_545_2048_R1.10_nominal_ringhalf_1.fits

HFI_SkyMap_545_2048_R1.10_nominal_ringhalf_2.fits

857GHz HFI_SkyMap_857_2048_R1.10_nominal_ringhalf_1.fits

HFI_SkyMap_857_2048_R1.10_nominal_ringhalf_2.fits

FITS file structure[edit]

FITS file structure

The FITS files for the sky maps contain a minimal primary header with no data, and a BINTABLE extension (EXTENSION 1, EXTNAME = FREQ-MAP) containing the data. The structure is shows schematically in the figure at right.

The FREQ-MAP extension contains is a 3-column table that contain the signal, hit-count and variance maps, all in Healpix format, in columns 1, 2, and 3, respectively. The number of rows is 50331648 for HFI and LFI 70 GHz at Nside=2048 and 12582912 for LFI maps at Nside=1024 (N.B: Npix = 12 Nside^2). The three columns are I_STOKES for the intensity (or temperature) signal, HIT for the hit-count and II_COV for the variance. The exact order of the columns in the figure is indicative only, and the details can be found in the keywords.

Keywords indicate the coordinate system (GALACTIC), the Healpix ordering scheme (NESTED), the units (K_cmb or MJy/sr) of each column, and of course the frequency channel (FREQ). The COMMENT fields give a one-line summary of the product, and some other information useful for traceability within the DPCs. The original filename is also given in the FILENAME keyword as are the datasum and the md5 checksum for the extension. The BAD_DATA keyword gives the value used by Healpix to indicate pixels for which no signal is present (these will also have a hit-count value of 0). The COMMENT fields give further information including some traceability data for the DPC's. The main parameters are summarised below:


Sky map file data structure
1. EXTNAME = 'FREQ-MAP' : Data columns
Column Name Data Type Units Description
I_STOKES Real*4 K_cmb or MJy/sr The signal map
HITS Int*4 none The hit-count map
II_COV Real*4 K_cmb2 or (MJy/sr)2 The variance map
Keyword Data Type Value Description
PIXTYPE string HEALPIX
COORDSYS string GALACTIC Coordinate system
ORDERING string NESTED Healpix ordering
NSIDE Int 1024 or 2048 Healpix Nside
FIRSTPIX Int*4 0 First pixel number
LASTPIX Int*4 12582911 or 50331647 Last pixel number
FREQ string nnn The frequency channel


The same structure applies to all SkyMap products, independent of whether they are full channel, survey of half-ring. The distinction between the types of maps is present in the FITS filename (and in the traceability comment fields).

References[edit]

  1. Planck 2013 results: HFI calibration and Map-making, Planck Collaboration 2013 VIII, A&A, in press, (2014).
  2. Planck 2013 results: LFI Calibration, Planck Collaboration 2013 V, A&A, in press, (2014).
  3. Planck 2013 results: The Low Frequency Instrument data processing, Planck Collaboration 2013 II, A&A, in press, (2014).

Cosmic Microwave background

(Planck) High Frequency Instrument

(Planck) Low Frequency Instrument

Flexible Image Transfer Specification

random telegraphic signal

analog to digital converter

[LFI meaning]: absolute calibration refers to the 0th order calibration for each channel, 1 single number, while the relative calibration refers to the component of the calibration that varies pointing period by pointing period.

To be confirmed

sudden change of the baseline level inside a ring

Attitude History File

[ESA's] Mission Operation Center [Darmstadt, Germany]

Line Of Sight

Noise Equivalent Temperature

Data Processing Center