Difference between revisions of "The RIMO"
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== Single detector and combined bandpasses == | == Single detector and combined bandpasses == | ||
Revision as of 12:52, 29 November 2012
Contents
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. 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. An example of the
;-----------------------------------------------------------------------------
; EXTENSION 176: BEAM_100-DS1x100-DS2
;-----------------------------------------------------------------------------
XTENSION= 'BINTABLE' /Written by IDL: Wed Aug 8 13:36:34 2012
BITPIX = 8 /
NAXIS = 2 /Binary table
NAXIS1 = 84000 /Number of bytes per row
NAXIS2 = 1 /Number of rows
PCOUNT = 0 /Random parameter count
GCOUNT = 1 /Group count
TFIELDS = 7 /Number of columns
COMMENT
COMMENT *** End of mandatory fields ***
COMMENT
EXTNAME = 'BEAM_100-DS1x100-DS2' /Extension name
PROCVER = 'v53/DX9 ' / HFI Product version
COMMENT
COMMENT *** Column names ***
COMMENT
TTYPE1 = 'BEAM ' /
TTYPE2 = 'BIAS ' /
TTYPE3 = 'VEC1 ' /
TTYPE4 = 'VEC2 ' /
TTYPE5 = 'VEC3 ' /
TTYPE6 = 'VEC4 ' /
TTYPE7 = 'VEC5 ' /
COMMENT
COMMENT *** Column formats ***
COMMENT
TFORM1 = '3000E ' /
TFORM2 = '3000E ' /
TFORM3 = '3000E ' /
TFORM4 = '3000E ' /
TFORM5 = '3000E ' /
TFORM6 = '3000E ' /
TFORM7 = '3000E ' /
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
