Difference between revisions of "Sky temperature maps"

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== Introduction ==
 +
 +
Frequency maps produced by combining appropriately the data of several detectors over some period of the mission.  They may be intensity only or polarized, meaning that they will consist of a set of three maps of I, Q, and U.  These will be accompanied by a hit-count map and by a set of variance maps.  The maps are packaged into a single ''BINTABLE'' extension; the structure of the FITS file is given in the [[#FITS file structure |FITS file structure]] section below.  The FITS filenames are of the form ''{H|L}FI_fff_2048_yyyymmdd_{type}_{mission}.fits'', where ''fff'' are three digits to indicated the Planck frequency band, ''2048'' is the Healpix Nside of the map, the optional ''type'' indicates the subset of input data used, and ''mission'' indicates the coverage period, i.e., ''full'', ''nominal'', or ''survey_n''.  A full list of products, by their names, is given in the [[#List of products | List of products]] below.
 +
 +
=== HFI processing ===
 +
 +
The cleaned and calibrated (in Watt) TOIs of each detector are first used to built Healpix rings. These are calibrated against the solar dipole, for the 100–353 GHz channels, and against FIRAS data for the 545–857 ones.  Gains are initially determined for each pointing period, but the correction is applied per pointing period only for the 100-217 GHz channels, where the dipole is strong enough to give a statistically significant correlation.  At the higher frequencies, the gains are averaged over the mission, and the single value is applied to all pointing periods.  The calibrated rings are then ''destriped'' in order to remove offsets introduced by the low frequency 1/f noise.  This is done by finding the ring crossings, and determining the scalar value to be added to each ring in order to minimize the offsets.  Finally, the rings corrected by the offsets are projected onto Healpix maps, with the data of each bolometer weighed by a factor of 1/NEP (TBC) of that bolometer. 
 +
 +
 +
=== LFI processing ===
 +
 +
TBW
 +
 +
== Types of maps ==
 +
 +
=== Full channel maps ===
 +
 +
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). 
 +
 +
=== 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.
 +
 +
{| border="1" cellpadding="5" cellspacing="0" align="center" style="text-align:center"
 +
|+ '''Missions and sky survey coverage periods'''
 +
! width="80"| Name    !! Ini_OD  !! Ini_Ring !! Ini_ptgID  !!  End_OD !! End_ring !! End_ptgID
 +
|-
 +
! align="left" | Nominal 
 +
|    91  ||    240  ||  00004200  ||    807  ||  14724  ||  04243900
 +
|-
 +
! align="left" | HFI-Full
 +
|    91  ||    240  ||  00004200  ||    563  ||  27008  ||  06344800
 +
|-
 +
! 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-nom   
 +
|  456  ||  11195  ||  02114530  ||    nnn  ||  nnn  ||  nnnn
 +
|-
 +
! align="left" | SCAN3-full
 +
|  456  ||  11195  ||  02114530  ||    636  ||  16691  ||  03193660
 +
|-
 +
! align="left" | SCAN4   
 +
|  636  ||  16692  ||  03193670  ||    807  ||  21720  ||  04243990
 +
|-
 +
! align="left" | SCAN5   
 +
|  807  ||  21721  ||  95000020  ||    974  ||  27008  ||  06344800 
 +
|}
 +
 +
 +
=== Detector-set maps ===
 +
 +
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 4 PSBs at the proper orientations.  The HFI polarized channels are designed to provide 2 detsets (or quads) each, namely:
 +
 +
{| class="wikitable"  align="center" style="text-align:center" border="1" cellpadding="5" cellspacing="0"
 +
|+ '''HFI detector sets or quads'''
 +
| '''100–ds1:''' 100-1a,100-1b,100-4a,100-4b || '''100–ds2:''' 100-2a,100-2b,100-3a,100-3b
 +
|-
 +
| '''143–ds1:''' 143-1a,143-1b,143-3a,143-3b || '''143–ds2:''' 143-2a,143-2b,143-4a,143-4b
 +
|-
 +
| '''217–ds1:''' 217-5a,217-5b,217-7a,217-7b || '''217–ds2:''' 217-6a,217-6b,217-8a,217-8b
 +
|-
 +
| '''353–ds1:''' 353-5a,353-5b,353-3a,353-3b || '''353–ds2:''' 353-6a,353-6b,353-4a,353-4b
 +
|}
 +
 +
=== 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.
 +
 +
 +
== List of products ==
 +
 +
=== First release ===
 +
 +
For the first release, all maps will be Intensity-only
 +
 +
; Full channel maps :
 +
LFI_030_2048_yyyymmdd_nominal.fits
 +
LFI_044_2048_yyyymmdd_nominal.fits
 +
LFI_070_2048_yyyymmdd_nominal.fits
 +
HFI_100_2048_yyyymmdd_nominal.fits
 +
HFI_143_2048_yyyymmdd_nominal.fits
 +
HFI_217_2048_yyyymmdd_nominal.fits
 +
HFI_353_2048_yyyymmdd_nominal.fits
 +
HFI_545_2048_yyyymmdd_nominal.fits
 +
HFI_857_2048_yyyymmdd_nominal.fits
 +
 +
; Single survey maps :
 +
LFI_030_2048_yyyymmdd_survey_1.fits
 +
LFI_030_2048_yyyymmdd_survey_2.fits
 +
LFI_030_2048_yyyymmdd_survey_3.fits
 +
LFI_044_2048_yyyymmdd_survey_1.fits
 +
LFI_044_2048_yyyymmdd_survey_2.fits
 +
LFI_044_2048_yyyymmdd_survey_3.fits
 +
LFI_070_2048_yyyymmdd_survey_1.fits
 +
LFI_070_2048_yyyymmdd_survey_2.fits
 +
LFI_070_2048_yyyymmdd_survey_3.fits
 +
HFI_100_2048_yyyymmdd_survey_1.fits
 +
HFI_100_2048_yyyymmdd_survey_2.fits
 +
HFI_100_2048_yyyymmdd_survey_3.fits
 +
HFI_143_2048_yyyymmdd_survey_1.fits
 +
HFI_143_2048_yyyymmdd_survey_2.fits
 +
HFI_143_2048_yyyymmdd_survey_3.fits
 +
HFI_217_2048_yyyymmdd_survey_1.fits
 +
HFI_217_2048_yyyymmdd_survey_2.fits
 +
HFI_217_2048_yyyymmdd_survey_3.fits
 +
HFI_353_2048_yyyymmdd_survey_1.fits
 +
HFI_353_2048_yyyymmdd_survey_2.fits
 +
HFI_353_2048_yyyymmdd_survey_3.fits
 +
HFI_545_2048_yyyymmdd_survey_1.fits
 +
HFI_545_2048_yyyymmdd_survey_2.fits
 +
HFI_545_2048_yyyymmdd_survey_3.fits
 +
HFI_857_2048_yyyymmdd_survey_1.fits
 +
HFI_857_2048_yyyymmdd_survey_2.fits
 +
HFI_857_2048_yyyymmdd_survey_3.fits
 +
 +
; Half-ring maps :
 +
LFI_030_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
LFI_030_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
LFI_044_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
LFI_044_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
LFI_070_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
LFI_070_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
HFI_100_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
HFI_100_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
HFI_143_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
HFI_143_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
HFI_217_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
HFI_217_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
HFI_353_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
HFI_353_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
HFI_545_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
HFI_545_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
HFI_857_2048_yyyymmdd_ringhalf_1_nominal.fits
 +
HFI_857_2048_yyyymmdd_ringhalf_2_nominal.fits
 +
 +
=== Second release ===
 +
 +
All the above + TBD, including polarization for the polarized frequency channels.
 +
 +
 +
== FITS file structure ==
 +
 +
 +
The FITS file will have one of the following structures:
 +
 +
 +
[[File:FITS_FreqMap.png | 500px  | center | thumb | '''FITS file structure''']]
 +
 +
The exact order of the columns is indicative only, and the details will be given in the keywords.  Keywords will also indicate the coordinate system (GALACTIC), the Healpix ordering scheme (NESTED), the units (K_cmb), and of course the detector.  Details of the FITS file general structure can be found in the EFDD (ref), and the specifics of certain parameters in ICD-031 (ref)
 +
 +
===Header keywords===
 +
 +
A typical header for the data extension of an intensity only map is:
 +
 +
XTENSION= 'BINTABLE'          / binary table extension                       
 +
BITPIX  =                    8 / 8-bit bytes                                   
 +
NAXIS  =                    2 / 2-dimensional binary table                   
 +
NAXIS1  =                  12 / width of table in bytes                       
 +
NAXIS2  =            50331648 / number of rows in table                       
 +
PCOUNT  =                    0 / size of special data area                     
 +
GCOUNT  =                    1 / one data group (required keyword)             
 +
TFIELDS =                    3 / number of fields in each row                 
 +
TTYPE1  = 'I_Stokes'          / label for field  1                           
 +
TFORM1  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT1  = 'K_CMB  '          / physical unit of field                       
 +
TTYPE2  = 'Hits    '          / label for field  2                           
 +
TFORM2  = '1J      '          / data format of field: 4-byte INTEGER         
 +
TUNIT2  = 'none    '          / physical unit of field                       
 +
TTYPE3  = 'II_cov  '          / label for field  3                           
 +
TFORM3  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT3  = '(K_CMB)^2'          / physical unit of field                       
 +
EXTNAME = 'CH-MAP  '          / name of this binary table extension           
 +
FREQ    = '857    '                                                           
 +
PIXTYPE = 'HEALPIX '                                                           
 +
COORDSYS= 'GALACTIC'                                                           
 +
ORDERING= 'NESTED  '                                                           
 +
FILENAME= 'HFI_857-2_2048_20120210_nominal.fits'                               
 +
NSIDE  =                2048                                                 
 +
CHANNEL = '857-2  '                                                           
 +
FIRSTPIX=                    0                                                 
 +
LASTPIX =            50331647                                                 
 +
EXTVER  = '1      '                                                           
 +
PROCVER = 'v50    '                                                           
 +
BAD_DATA= '-1.63750E+30'                                                       
 +
COMMENT = 'Rel DR4 '                                                           
 +
END
 +
 +
and for a polarized frequency map:
 +
 +
XTENSION= 'BINTABLE'          / binary table extension                       
 +
BITPIX  =                    8 / 8-bit bytes                                   
 +
NAXIS  =                    2 / 2-dimensional binary table                   
 +
NAXIS1  =                  40 / width of table in bytes                       
 +
NAXIS2  =            50331648 / number of rows in table                       
 +
PCOUNT  =                    0 / size of special data area                     
 +
GCOUNT  =                    1 / one data group (required keyword)             
 +
TFIELDS =                  10 / number of fields in each row                 
 +
TTYPE1  = 'I_Stokes'          / label for field  1                           
 +
TFORM1  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT1  = 'K_CMB  '          / physical unit of field                       
 +
TTYPE2  = 'Q_Stokes'          / label for field  2                           
 +
TFORM2  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT2  = 'K_CMB  '          / physical unit of field                       
 +
TTYPE3  = 'U_Stokes'          / label for field  3                           
 +
TFORM3  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT3  = 'K_CMB  '          / physical unit of field                       
 +
TTYPE4  = 'Hits    '          / label for field  4                           
 +
TFORM4  = '1J      '          / data format of field: 4-byte INTEGER         
 +
TUNIT4  = 'none    '          / physical unit of field                       
 +
TTYPE5  = 'II_cov  '          / label for field  5                           
 +
TFORM5  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT5  = '(K_CMB)^2'          / physical unit of field                       
 +
TTYPE6  = 'IQ_cov  '          / label for field  6                           
 +
TFORM6  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT6  = '(K_CMB)^2'          / physical unit of field                       
 +
TTYPE7  = 'IU_cov  '          / label for field  7                           
 +
TFORM7  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT7  = '(K_CMB)^2'          / physical unit of field                       
 +
TTYPE8  = 'QQ_cov  '          / label for field  8                           
 +
TFORM8  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT8  = '(K_CMB)^2'          / physical unit of field                       
 +
TTYPE9  = 'QU_cov  '          / label for field  9                           
 +
TFORM9  = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT9  = '(K_CMB)^2'          / physical unit of field                       
 +
TTYPE10 = 'UU_cov  '          / label for field  10                           
 +
TFORM10 = '1E8    '          / data format of field: 4-byte REAL             
 +
TUNIT10 = '(K_CMB)^2'          / physical unit of field                       
 +
EXTNAME = 'FR-MAP  '          / name of this binary table extension           
 +
FREQ    = '217    '                                                           
 +
PIXTYPE = 'HEALPIX '                                                           
 +
COORDSYS= 'GALACTIC'                                                           
 +
ORDERING= 'NESTED  '                                                           
 +
FILENAME= 'HFI_217_2048_20120210_nominal.fits'                                 
 +
NSIDE  =                2048                                                 
 +
FIRSTPIX=                    0                                                 
 +
LASTPIX =            50331647                                                 
 +
EXTVER  = '1      '                                                           
 +
PROCVER = 'v50    '                                                           
 +
BAD_DATA= '-1.63750E+30'                                                       
 +
COMMENT = 'Rel DR4 '                                                           
 +
END
 +
 
[[Category:Mission science products]]
 
[[Category:Mission science products]]

Revision as of 16:56, 20 August 2012

Introduction[edit]

Frequency maps produced by combining appropriately the data of several detectors over some period of the mission. They may be intensity only or polarized, meaning that they will consist of a set of three maps of I, Q, and U. These will be accompanied by a hit-count map and by a set of variance maps. The maps are packaged into a single BINTABLE extension; the structure of the FITS file is given in the FITS file structure section below. The FITS filenames are of the form {H|L}FI_fff_2048_yyyymmdd_{type}_{mission}.fits, where fff are three digits to indicated the Planck frequency band, 2048 is the Healpix Nside of the map, the optional type indicates the subset of input data used, and mission indicates the coverage period, i.e., full, nominal, or survey_n. A full list of products, by their names, is given in the List of products below.

HFI processing[edit]

The cleaned and calibrated (in Watt) TOIs of each detector are first used to built Healpix rings. These are calibrated against the solar dipole, for the 100–353 GHz channels, and against FIRAS data for the 545–857 ones. Gains are initially determined for each pointing period, but the correction is applied per pointing period only for the 100-217 GHz channels, where the dipole is strong enough to give a statistically significant correlation. At the higher frequencies, the gains are averaged over the mission, and the single value is applied to all pointing periods. The calibrated rings are then destriped in order to remove offsets introduced by the low frequency 1/f noise. This is done by finding the ring crossings, and determining the scalar value to be added to each ring in order to minimize the offsets. Finally, the rings corrected by the offsets are projected onto Healpix maps, with the data of each bolometer weighed by a factor of 1/NEP (TBC) of that bolometer.


LFI processing[edit]

TBW

Types of maps[edit]

Full channel maps[edit]

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).

Single survey maps[edit]

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.

Missions and sky survey coverage periods
Name Ini_OD Ini_Ring Ini_ptgID End_OD End_ring End_ptgID
Nominal 91 240 00004200 807 14724 04243900
HFI-Full 91 240 00004200 563 27008 06344800
LFI-Full 91 240 00004200 TBD TBD TBD
SCAN1 91 240 00004200 270 5720 01059820
SCAN2 270 5721 01059830 456 11194 02114520
SCAN3-nom 456 11195 02114530 nnn nnn nnnn
SCAN3-full 456 11195 02114530 636 16691 03193660
SCAN4 636 16692 03193670 807 21720 04243990
SCAN5 807 21721 95000020 974 27008 06344800


Detector-set maps[edit]

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 4 PSBs at the proper orientations. The HFI polarized channels are designed to provide 2 detsets (or quads) each, namely:

HFI detector sets or quads
100–ds1: 100-1a,100-1b,100-4a,100-4b 100–ds2: 100-2a,100-2b,100-3a,100-3b
143–ds1: 143-1a,143-1b,143-3a,143-3b 143–ds2: 143-2a,143-2b,143-4a,143-4b
217–ds1: 217-5a,217-5b,217-7a,217-7b 217–ds2: 217-6a,217-6b,217-8a,217-8b
353–ds1: 353-5a,353-5b,353-3a,353-3b 353–ds2: 353-6a,353-6b,353-4a,353-4b

Half-ring maps[edit]

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.


List of products[edit]

First release[edit]

For the first release, all maps will be Intensity-only

Full channel maps 
LFI_030_2048_yyyymmdd_nominal.fits
LFI_044_2048_yyyymmdd_nominal.fits
LFI_070_2048_yyyymmdd_nominal.fits
HFI_100_2048_yyyymmdd_nominal.fits
HFI_143_2048_yyyymmdd_nominal.fits
HFI_217_2048_yyyymmdd_nominal.fits
HFI_353_2048_yyyymmdd_nominal.fits
HFI_545_2048_yyyymmdd_nominal.fits
HFI_857_2048_yyyymmdd_nominal.fits
Single survey maps 
LFI_030_2048_yyyymmdd_survey_1.fits
LFI_030_2048_yyyymmdd_survey_2.fits
LFI_030_2048_yyyymmdd_survey_3.fits
LFI_044_2048_yyyymmdd_survey_1.fits
LFI_044_2048_yyyymmdd_survey_2.fits
LFI_044_2048_yyyymmdd_survey_3.fits
LFI_070_2048_yyyymmdd_survey_1.fits
LFI_070_2048_yyyymmdd_survey_2.fits
LFI_070_2048_yyyymmdd_survey_3.fits
HFI_100_2048_yyyymmdd_survey_1.fits
HFI_100_2048_yyyymmdd_survey_2.fits
HFI_100_2048_yyyymmdd_survey_3.fits
HFI_143_2048_yyyymmdd_survey_1.fits
HFI_143_2048_yyyymmdd_survey_2.fits
HFI_143_2048_yyyymmdd_survey_3.fits
HFI_217_2048_yyyymmdd_survey_1.fits
HFI_217_2048_yyyymmdd_survey_2.fits
HFI_217_2048_yyyymmdd_survey_3.fits
HFI_353_2048_yyyymmdd_survey_1.fits
HFI_353_2048_yyyymmdd_survey_2.fits
HFI_353_2048_yyyymmdd_survey_3.fits
HFI_545_2048_yyyymmdd_survey_1.fits
HFI_545_2048_yyyymmdd_survey_2.fits
HFI_545_2048_yyyymmdd_survey_3.fits
HFI_857_2048_yyyymmdd_survey_1.fits
HFI_857_2048_yyyymmdd_survey_2.fits
HFI_857_2048_yyyymmdd_survey_3.fits
Half-ring maps 
LFI_030_2048_yyyymmdd_ringhalf_1_nominal.fits
LFI_030_2048_yyyymmdd_ringhalf_2_nominal.fits
LFI_044_2048_yyyymmdd_ringhalf_1_nominal.fits
LFI_044_2048_yyyymmdd_ringhalf_2_nominal.fits
LFI_070_2048_yyyymmdd_ringhalf_1_nominal.fits
LFI_070_2048_yyyymmdd_ringhalf_2_nominal.fits
HFI_100_2048_yyyymmdd_ringhalf_1_nominal.fits
HFI_100_2048_yyyymmdd_ringhalf_2_nominal.fits
HFI_143_2048_yyyymmdd_ringhalf_1_nominal.fits
HFI_143_2048_yyyymmdd_ringhalf_2_nominal.fits
HFI_217_2048_yyyymmdd_ringhalf_1_nominal.fits
HFI_217_2048_yyyymmdd_ringhalf_2_nominal.fits
HFI_353_2048_yyyymmdd_ringhalf_1_nominal.fits
HFI_353_2048_yyyymmdd_ringhalf_2_nominal.fits
HFI_545_2048_yyyymmdd_ringhalf_1_nominal.fits
HFI_545_2048_yyyymmdd_ringhalf_2_nominal.fits
HFI_857_2048_yyyymmdd_ringhalf_1_nominal.fits
HFI_857_2048_yyyymmdd_ringhalf_2_nominal.fits

Second release[edit]

All the above + TBD, including polarization for the polarized frequency channels.


FITS file structure[edit]

The FITS file will have one of the following structures:


FITS file structure

The exact order of the columns is indicative only, and the details will be given in the keywords. Keywords will also indicate the coordinate system (GALACTIC), the Healpix ordering scheme (NESTED), the units (K_cmb), and of course the detector. Details of the FITS file general structure can be found in the EFDD (ref), and the specifics of certain parameters in ICD-031 (ref)

Header keywords[edit]

A typical header for the data extension of an intensity only map is: 

XTENSION= 'BINTABLE'           / binary table extension                         
BITPIX  =                    8 / 8-bit bytes                                    
NAXIS   =                    2 / 2-dimensional binary table                     
NAXIS1  =                   12 / width of table in bytes                        
NAXIS2  =             50331648 / number of rows in table                        
PCOUNT  =                    0 / size of special data area                      
GCOUNT  =                    1 / one data group (required keyword)              
TFIELDS =                    3 / number of fields in each row                   
TTYPE1  = 'I_Stokes'           / label for field   1                            
TFORM1  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT1  = 'K_CMB   '           / physical unit of field                         
TTYPE2  = 'Hits    '           / label for field   2                            
TFORM2  = '1J      '           / data format of field: 4-byte INTEGER           
TUNIT2  = 'none    '           / physical unit of field                         
TTYPE3  = 'II_cov  '           / label for field   3                            
TFORM3  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT3  = '(K_CMB)^2'          / physical unit of field                         
EXTNAME = 'CH-MAP  '           / name of this binary table extension            
FREQ    = '857     '                                                            
PIXTYPE = 'HEALPIX '                                                            
COORDSYS= 'GALACTIC'                                                            
ORDERING= 'NESTED  '                                                            
FILENAME= 'HFI_857-2_2048_20120210_nominal.fits'                                
NSIDE   =                 2048                                                  
CHANNEL = '857-2   '                                                            
FIRSTPIX=                    0                                                  
LASTPIX =             50331647                                                  
EXTVER  = '1       '                                                            
PROCVER = 'v50     '                                                            
BAD_DATA= '-1.63750E+30'                                                        
COMMENT = 'Rel DR4 '                                                            
END

and for a polarized frequency map: 

XTENSION= 'BINTABLE'           / binary table extension                         
BITPIX  =                    8 / 8-bit bytes                                    
NAXIS   =                    2 / 2-dimensional binary table                     
NAXIS1  =                   40 / width of table in bytes                        
NAXIS2  =             50331648 / number of rows in table                        
PCOUNT  =                    0 / size of special data area                      
GCOUNT  =                    1 / one data group (required keyword)              
TFIELDS =                   10 / number of fields in each row                   
TTYPE1  = 'I_Stokes'           / label for field   1                            
TFORM1  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT1  = 'K_CMB   '           / physical unit of field                         
TTYPE2  = 'Q_Stokes'           / label for field   2                            
TFORM2  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT2  = 'K_CMB   '           / physical unit of field                         
TTYPE3  = 'U_Stokes'           / label for field   3                            
TFORM3  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT3  = 'K_CMB   '           / physical unit of field                         
TTYPE4  = 'Hits    '           / label for field   4                            
TFORM4  = '1J      '           / data format of field: 4-byte INTEGER           
TUNIT4  = 'none    '           / physical unit of field                         
TTYPE5  = 'II_cov  '           / label for field   5                            
TFORM5  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT5  = '(K_CMB)^2'          / physical unit of field                         
TTYPE6  = 'IQ_cov  '           / label for field   6                            
TFORM6  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT6  = '(K_CMB)^2'          / physical unit of field                         
TTYPE7  = 'IU_cov  '           / label for field   7                            
TFORM7  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT7  = '(K_CMB)^2'          / physical unit of field                         
TTYPE8  = 'QQ_cov  '           / label for field   8                            
TFORM8  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT8  = '(K_CMB)^2'          / physical unit of field                         
TTYPE9  = 'QU_cov  '           / label for field   9                            
TFORM9  = '1E8     '           / data format of field: 4-byte REAL              
TUNIT9  = '(K_CMB)^2'          / physical unit of field                         
TTYPE10 = 'UU_cov  '           / label for field  10                            
TFORM10 = '1E8     '           / data format of field: 4-byte REAL              
TUNIT10 = '(K_CMB)^2'          / physical unit of field                         
EXTNAME = 'FR-MAP  '           / name of this binary table extension            
FREQ    = '217     '                                                            
PIXTYPE = 'HEALPIX '                                                            
COORDSYS= 'GALACTIC'                                                            
ORDERING= 'NESTED  '                                                            
FILENAME= 'HFI_217_2048_20120210_nominal.fits'                                  
NSIDE   =                 2048                                                  
FIRSTPIX=                    0                                                  
LASTPIX =             50331647                                                  
EXTVER  = '1       '                                                            
PROCVER = 'v50     '                                                            
BAD_DATA= '-1.63750E+30'                                                        
COMMENT = 'Rel DR4 '                                                            
END

Flexible Image Transfer Specification

(Planck) High Frequency Instrument

Noise Equivalent Power

To be confirmed

(Planck) Low Frequency Instrument

Operation Day definition is geometric visibility driven as it runs from the start of a DTCP (satellite Acquisition Of Signal) to the start of the next DTCP. Given the different ground stations and spacecraft will takes which station for how long, the OD duration varies but it is basically once a day.

To be defined / determined

Interface Control Document

Cosmic Microwave background

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