Difference between revisions of "The RIMO"

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== Overview ==
 
== Overview ==
  
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.  There will be two RIMOs, one for each instrument, which will follow the same overall structure, but will differ in the details.  
+
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:
The type of data in the RIMO can be:
 
  
 
; Parameter : namely scalers to give properties such as a noise level or a representative beam FWHM
 
; Parameter : namely scalers to give properties such as a noise level or a representative beam FWHM
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<center>
 
<center>
{| border="1" cellspacing="0" cellpadding="5" align="center" style="background:yellow; color:maroon; font-size:150%"  width="600px"
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{| border="1" cellspacing="10" cellpadding="8" align="center" style="background:yellow; color:maroon; font-size:150%"  width="600px"
! There  are no detector-level products in the first release, so there will be no detector-level parameters in the accompanying RIMO.  This section will serve for later releases.
+
! There  are no detector-level products in the first release,  
 +
 
 +
so there will be no detector-level parameters in the accompanying RIMO.   
 +
 
 +
This section will serve for later releases.
 
|}
 
|}
 
</center>
 
</center>
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; ''DETECTOR'':  
 
; ''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.
+
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.
  
; ''PHI_UV'', ''THETA_UV'', and ''PSI_UV'' :  
+
; Focal plane geometry parameters - ''PHI_UV'', ''THETA_UV'', and ''PSI_UV'' :  
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. All angles are in radians
+
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.
  
; ''PSI_POL'' :
+
; Polarization parameters - ''PSI_POL'', ''EPSILON'' :
is the direction of maximum polarization, defined with the beam in the fiducial orientation described above, that is, before rotation onto the detector position.
+
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).  
  
; ''EPSILON'' :
+
; Beam parameters - ''FWHM'', ''ELLIPTICITY'', ''POSANG'' :  
the cross-polarization contamination (or leackage).  
+
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.
  
; ''FWHM'' : the mean FWHM of the beam (arcmin TBC).
+
; 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).
  
; ''ELLIPTICITY'' : the beam ellipticity (no units)
 
  
; ''POSANG'' : the position angle of the beam major axis
+
== Map-level parameter data ==
  
 +
; ''FREQUENCY'' : a 3-digit string giving the reference frequency in GHz, i.e., of the form ''044'' or ''217''
  
 +
; Beam parameters - ''FWHM'' ;
 +
These are the FWHM (in rad) of the effective beam and its solid angle (in sr)
  
 +
; Noise parameter - ''NOISE'' ;
 +
This is TBD: noise/observation sample or ...
  
== Map-level parameter data ==
+
== Single detector and 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
 +
* the wavenumber (cm-1)
 +
* the transmission (normalized to 1 at the max for HFI and to have an integral of 1 for LFI)
 +
* the uncertainty
 +
* a flag
  
 
== Detector noise spectra ==
 
== Detector noise spectra ==
 +
 +
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.
  
  
 
== Beam Window Functions ==
 
== Beam Window Functions ==
  
 +
Beam window functions and associated error descriptions are given into a BINTABLE for each ''detection unit''. The ''NOMINAL'' column is mandatory, the ''BIAS'' column is optional, and the number of ''EVECT'' is variable. The keyword ''NEVEC'' indicates how many there are in order to ease the automatic reading
  
 
== FITS file structure ==
 
== FITS file structure ==

Revision as of 16:22, 18 October 2012

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 scalers to give properties such as a noise level or a representative beam FWHM
Table 
to give filter transmission profiles or noise power spectra
Map 
to give beam shape

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


Outstanding business:

  • common or mixed items, like, eventually cross beam window functions between an HFI and an LFI beam


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.

This section will serve for later releases.


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).


Map-level parameter data[edit]

FREQUENCY 
a 3-digit string giving the reference frequency in GHz, i.e., of the form 044 or 217
Beam parameters - FWHM ;

These are the FWHM (in rad) of the effective beam and its solid angle (in sr)

Noise parameter - NOISE ;

This is TBD: noise/observation sample or ...

Single detector and combined bandpasses[edit]

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

  • the wavenumber (cm-1)
  • the transmission (normalized to 1 at the max for HFI and to have an integral of 1 for LFI)
  • the uncertainty
  • a flag

Detector noise spectra[edit]

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.


Beam Window Functions[edit]

Beam window functions and associated error descriptions are given into a BINTABLE for each detection unit. The NOMINAL column is mandatory, the BIAS column is optional, and the number of EVECT is variable. The keyword NEVEC indicates how many there are in order to ease the automatic reading

FITS file structure[edit]

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