The RIMO

From Planck Legacy Archive Wiki
Revision as of 13:13, 29 November 2012 by Amoneti (talk | contribs) (Beam Window Functions)
Jump to: navigation, search

Overview[edit]

The RIMO, or Reduced Instrument Model is a FITS file containing selected instrument characteristics that are needed by users who work with the released data products. It is described in detail in The HFI and LFI RIMO ICD (ref). There will be two RIMOs, one for each instrument, which will follow the same overall structure, but will differ in the details. The type of data in the RIMO can be:

Parameter 
namely scalars to give properties such as a noise level or a representative beam FWHM
Table 
to give, e.g., filter transmission profiles or noise power spectra
Map 
namely 2-D "flat" maps, to give, e.g., the main beam shape

The different types of data are written into different BINTABLE extensions of the FITS file, and these are described below.



Detector-level parameter data[edit]

There are no detector-level products in the first release,

so there will be no detector-level parameters in the accompanying RIMO.


The detector parameter data are given in the form of a table giving the parameter values for each detector. The table columns are (with the column names in parentheses):

DETECTOR 
These are the detector names. For HFI these will be of the form 217-3 for SWBs or 100-3b for PSBs, and for LFI they will have the form 27M or 18S. There are 52 HFI detectors and 22 LFI detectors.
Focal plane geometry parameters - PHI_UV, THETA_UV, and PSI_UV 
These parameters give the geometry of the focal plane, or the positions of the detectors in the focal plane. The angles that give the rotation of the beam pattern from a fiducial orientation (forward beam direction (z-axis) pointing along the telescope line of sight, with y-axis aligned with the nominal scan direction) to their positions in the focal plane. The fiducial position is that given by the Star Tracker. All angles are in radians.
Polarization parameters - PSI_POL, EPSILON 
These are the direction of maximum polarization, defined with the beam in the fiducial orientation described above, that is, before rotation onto the detector position, and the cross-polarization contamination (or leakage).
Beam parameters - FWHM, ELLIPTICITY, POSANG 
These are the mean FWHM of the scanning beam (arcmin TBC), the beam ellipticity (no units), and the position angle of the beam major axis. The scanning beam is that recovered from the observation of bright planets.
Noise parameters - NET_TOT, NET_WHT, F_KNEE, ALPHA 
Two NETs are given: one determined from the total noise (rms of the noise timeline) and one determined from the white noise level of the noise spectrum. The F_KNEE and ALPHA parameters are the frequency where the 1/f noise component meets the white noise level, and the slope of the former. The NETs are in units of Kcmb or MJy/sr * sqrt(s).

The basic structure of the BINTABLE extension is as follows:


;-----------------------------------------------------------------------------
; Detector parameters
;-----------------------------------------------------------------------------
XTENSION= 'BINTABLE'           / binary table extension                         
BITPIX  =                    8 / array data type                                
NAXIS   =                    2 / number of array dimensions                     
NAXIS1  =                  120 / length of dimension 1                          
NAXIS2  =                   52 / length of dimension 2                          
PCOUNT  =                    0 / number of group parameters                     
GCOUNT  =                    1 / number of groups                               
TFIELDS =                   15 / number of table fields                         
EXTNAME = 'CHANNEL PARAMETERS' / extension name                                 
TTYPE1  = 'DETECTOR'                                                            
TFORM1  = '8A      '                                                            
TUNIT1  = 'n/a     '                                                            
TTYPE2  = 'PHI_UV  '                                                            
TFORM2  = 'D       '                                                            
TUNIT2  = 'deg     '                                                            
TTYPE3  = 'THETA_UV'                                                            
TFORM3  = 'D       '                                                            
TUNIT3  = 'deg     '                                                            
TTYPE4  = 'PSI_UV  '                                                            
TFORM4  = 'D       '                                                            
TUNIT4  = 'deg     '                                                            
TTYPE5  = 'PSI_POL '                                                            
TFORM5  = 'D       '                                                            
TUNIT5  = 'deg     '                                                            
TTYPE6  = 'EPSILON '                                                            
TFORM6  = 'D       '                                                            
TUNIT6  = 'n/a     '                                                            
TTYPE7  = 'FWHM    '                                                            
TFORM7  = 'D       '                                                            
TUNIT7  = 'arcmin  '                                                            
TTYPE8  = 'ELLIPTICITY'                                                         
TFORM8  = 'D       '                                                            
TUNIT8  = 'n/a     '                                                            
TTYPE9  = 'POSANG  '                                                            
TFORM9  = 'D       '                                                            
TUNIT9  = 'deg     '                                                            
TTYPE10 = 'NET     '                                                            
TFORM10 = 'D       '                                                            
TUNIT10 = 'K*s^1/2 '                                                            
TTYPE11 = 'F_KNEE  '                                                            
TFORM11 = 'D       '                                                            
TUNIT11 = 'Hz      '                                                            
TTYPE12 = 'ALPHA   '                                                            
TFORM12 = 'D       '                                                            
TUNIT12 = 'n/a     '                                                            
TTYPE13 = 'F_MIN   '                                                            
TFORM13 = 'D       '                                                            
TUNIT13 = 'Hz      '                                                            
TTYPE14 = 'F_MAX   '                                                            
TFORM14 = 'D       '                                                            
TUNIT14 = 'Hz      '                                                            
TTYPE15 = 'F_SAMP  '                                                            
TFORM15 = 'D       '                                                            
TUNIT15 = 'Hz      '

Map-level parameter data[edit]

The map-level data table contains the beam solid angle (total and out to different FWHM) and noise information as follows:

FREQUENCY 
a 3-digit string giving the reference frequency in GHz, i.e., of the form 044 or 217
Omega_total
total beam solid angle in armin^2
Ometa_1fwhm 
beam solid angle out to 1FWHM in arcmin^2
Omega_2fwhm 
beam solid angle out to 2FWHM in arcmin^2
FWHM_eff 
FWHM of a Gaussian beam having the same (total) solid angle, in sr. This is the best value for source flux determination
FWHM_gauss 
FWHM derived from best Gaussian fit to beam maps, in sr. This is the best value for source identification
Noise parameter - NOISE 
This is TBD: noise/observation sample or ...

The BINTABLE extension has the following structure

TABLE TO BE ADDED

Single detector and combined bandpasses[edit]

There are no detector-level products in the first release,

so there will be no detector-level badnpasses in the accompanying RIMO, but only the combined bandpasses


The effective filter bandpasses are given in different BINTABLE extensions. The extension is named BANDPASS_{name}, where name specified the detector or the map. In the case of the maps, the bandpasses are a weighted average of the bandpasses of the detectors that are used to built the map. For details see ref to 03d HFI_Spectral Band. The bandpasses are given as 4-column tables containing

WAVENUMBER 
the wavenumber in cm-1
TRANSMISSION 
the transmission (normalized to 1 at the max for HFI and to have an integral of 1 for LFI)
ERROR 
the uncertainty
FLAG 
a flag

The BINTABLE extension has the following structure

;-----------------------------------------------------------------------------
; Bandpasses (detector or combined)
;-----------------------------------------------------------------------------
XTENSION= 'BINTABLE'           / binary table extension                         
BITPIX  =                    8 / array data type                                
NAXIS   =                    2 / number of array dimensions                     
NAXIS1  =                   25 / length of dimension 1                          
NAXIS2  =                12315 / length of dimension 2                          
PCOUNT  =                    0 / number of group parameters                     
GCOUNT  =                    1 / number of groups                               
TFIELDS =                    4 / number of table fields                         
EXTNAME = 'BANDPASS_100-2A'    / extension name                                 
TTYPE1  = 'WAVENUMBER'                                                          
TFORM1  = 'D       '                                                            
TUNIT1  = '1/cm    '                                                            
TTYPE2  = 'TRANSMISSION'                                                        
TFORM2  = 'D       '                                                            
TUNIT2  = 'n/a     '                                                            
TTYPE3  = 'UNCERTAINTY'                                                         
TFORM3  = 'D       '                                                            
TUNIT3  = 'n/a     '                                                            
TTYPE4  = 'FLAG    '                                                            
TFORM4  = 'L       '                                                            
TUNIT4  = 'n/a     '                                                            
COMMENT Spencer v2.02 injection                                                 
END

Detector noise spectra[edit]

There are no detector-level products in the first release,

so there will be no detector noise spectra in the accompanying RIMO.


The noise power spectra are the result of the detnoise pipeline.

HFI
these are the ring noise spectra averaged for rings NN to MM in order to give a representative spectrum. The spectra of all 50 valid bolometers are given in a single table.
LFI 
TBW

The keyword F_NYQ gives the Nyquist frequency, and can be used together with the number of points in the spectrum to reconstruct the frequency scale. The BINTABLE has the following structure:

XTENSION= 'BINTABLE'           /Written by IDL:  Wed Aug  8 13:36:33 2012       
BITPIX  =                    8 /                                                
NAXIS   =                    2 /Binary table                                    
NAXIS1  =             13631488 /Number of bytes per row                         
NAXIS2  =                    1 /Number of rows                                  
PCOUNT  =                    0 /Random parameter count                          
GCOUNT  =                    1 /Group count                                     
TFIELDS =                   52 /Number of columns                               
COMMENT                                                                         
COMMENT  *** End of mandatory fields ***                                        
COMMENT                                                                         
EXTNAME = 'NOISE_SPECTRA'      /Extension name                                  
DBPATH  = '/data/dmc/MISS03/DATA/detnoise/' /                                   
TAG     = '_MeanSpectrum_deconv_byRing_p17_survey_3_v53' /                      
N_PTS   =                65536 /                                                
F_NYQ   =              90.0000 /                                                
UNITS   = 'W/rt(Hz)'           /                                                
PROCVER = 'v53/DX9 '           / HFI Product version                            
COMMENT                                                                         
COMMENT  *** Column names ***                                                   
COMMENT                                                                         
TTYPE1  = 'SPECTRUM_100_1A'    /                                                
TTYPE2  = 'SPECTRUM_100_1B'    /                                                
....
                             
TTYPE52 = 'SPECTRUM_857_4'     /                                                
COMMENT                                                                         
COMMENT  *** Column formats ***                                                 
COMMENT                                                                         
TFORM1  = '65536E  '           /                                                
TFORM2  = '65536E  '           /                                                
....
                                       
TFORM52 = '65536E  '           /                                                
END

Beam Window Functions[edit]

Beam window functions and associated error descriptions are given into a BINTABLE for each detection unit, where detection unit consists of an auto or a cross product of one or two frequency maps or detset maps used in the likelihood. Here they are:

  • the 6 HFI frequency channels, producing 21 extensions
  • 26 detsets, producing 351 extensions; the detsets used are, by frequency channel:
    • 100_ds1, 100_ds2,
    • 143_ds1, 143_ds2, 143_5, 143_6, 143_7,
    • 217_ds1, 217_ds2, 217_1, 217_2, 217_3, 217_4,
    • 353_ds1, 353_ds2, 353_1, 353_2, 353_7, 353_8,
    • 545_1, 545_2, 545_4,
    • 857_1, 857_2, 857_3, 857_4


Each extension contains:

  • a NOMINAL column (mandatory) with the window function proper,
  • a BIAS column (optional),
  • a number of EIGEN_n vectors, 5 for Release 1) of error modes.
  • a keyword NUMVECT (Integer) specified the number of eigenmode vectors, and
  • the keyword NAXIS2 gives the length of each vector

An example of the FITS header is:

;-----------------------------------------------------------------------------
; EXTENSION 11: BEAM_143_DS1X143_5
;----------------------------------------------------------------------------- 
XTENSION= 'BINTABLE'           / binary table extension                           
BITPIX  =                    8 / array data type                                 
NAXIS   =                    2 / number of array dimensions                     
NAXIS1  =                   24 / length of dimension 1                          
NAXIS2  =                 4001 / length of dimension 2                          
PCOUNT  =                    0 / number of group parameters                     
GCOUNT  =                    1 / number of groups                               
TFIELDS =                    6 / number of table fields                         
TTYPE1  = 'NOMINAL '                                                            
TFORM1  = 'E       '                                                            
TTYPE2  = 'EIGEN_0 '                                                            
TFORM2  = 'E       '                                                            
TTYPE3  = 'EIGEN_1 '                                                            
TFORM3  = 'E       '                                                            
TTYPE4  = 'EIGEN_2 '                                                            
TFORM4  = 'E       '                                                            
TTYPE5  = 'EIGEN_3 '                                                            
TFORM5  = 'E       '                                                            
TTYPE6  = 'EIGEN_4 '                                                            
TFORM6  = 'E       '                                                            
EXTNAME = 'BEAM_143_DS1X143_5' / extension name                                 
NUMVECT =                    5 / Number of eigenvectors                         
END

reduced IMO

Flexible Image Transfer Specification

(Planck) High Frequency Instrument

(Planck) Low Frequency Instrument

Interface Control Document

Full-Width-at-Half-Maximum

To be confirmed

Noise Equivalent Temperature

To be defined / determined