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| − | There will be no timelines in the 1st data release …
| + | <span style="color:green; font-size:150%">'''This section was intentionally left empty. It will be filled in future releases of the PLA to accompany the Timeline products.'''</span> |
| − | | + | [[Category:Mission products|001]] |
| − | == Semi-raw signal timelines ==
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| − | | |
| − | === HFI timelines ===
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| − | Originally defined to be the raw (ADU) data demodulated and converted to engineering units (V) via the HFI transfer functions (includes 3-pt filtering?). But (1) this is not the same demodulation method as used in the TOI prod pipeline, and (2) the ADC correction (or at least one method thereof) implies a modification of the raw data before demodulation. Thus what the HFI will deliver is not yet decided
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| − | === LFI timelines === | |
| − | | |
| − | TBW
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| − | == Cleaned and calibrated signal timelines ==
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| − | | |
| − | === HFI processing ===
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| − | | |
| − | The calibrated timelines are produced by the ''TOIprod'' pipeline (link to wiki; link to paper) which in brief performs the following operations:
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| − | ; demodulation: this is performed around a variable level which is determined from the valid input data (a validity flat from a previous version of the processing is determined for this purpose), and the data are converted to engineering units (V) using known conversion coefficients.
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| − | ; 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 TBC ''(is this done here, if not where?)''
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| − | ; dark template removal: ''TBW''
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| − | ; 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: ''TBW''
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| − | at this point a timeline in W and a glitch flag are written to disk
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| − | ; deconvolution by the time transfer function: ''TBW''
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| − | ; jump correction: removes some (relatively rare) jumps in the signal baseline
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| − | at this point a ''tau-deconvolved'' and ''jump-corrected'' timeline and its associated glitch flag are written to disk. These timelines are later used in the flux calibration and mapmaking stages
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| − | Note that these timelines contain the full sky signal, i.e. including the solar and orbital dipoles and the Zodiacal light. The dipoles are necessary for the flux calibration and are removed by the pipeline at the mapmaking stage.
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| − | '''Need to discuss dipoles removal and conversion to astrophysical units at the export stage'''
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| − | | |
| − | === LFI processing ===
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| − | | |
| − | TBW
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| − | == Pointing timelines ==
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| − | 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).
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| − | ''Details of delivery are TBD''
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| − | | |
| − | == FITS file structure ==
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| − | The FITS files will begin with a minimal primary header that will be followed by several BINTABLE extensions: the first one for the OBT and its (global) flag, the following ones for each detector signal data and its (local) flag.
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| − | Filenames will be of the form ''{H|L}FI_HscN-DDDD-R-yyymmdd.fits'', where ''DDDD'' is the OD number, ''sc'' indicates science data, and N=1-5 for the 5 HFI files, and ''R'' indicates it is reduced (i.e., cleaned and calibrated) data.
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| − | ''NB. this is the current name used in DPC exchanges, perhaps it should be changed … eg. replace the date with the release number. Will also indicate that they are calibrated in astrophysical units and will have the dipoles removed, thus they are for delivery to the external community.''
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| − | | |
| − | === Header keywords ===
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| − | | |
| − | An example is given below.
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| − |
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| − | ==== EXTENSION 0: ====
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| − | SIMPLE = T / file does conform to FITS standard
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| − | BITPIX = 32 / number of bits per data pixel
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| − | NAXIS = 0 / number of data axes
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| − | EXTEND = T / FITS dataset may contain extensions
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| − | COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
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| − | COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
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| − | EFDD_VER= '99.9 '
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| − | ICD_VER = '99.9 '
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| − | IMO = 'IMO_2_62'
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| − | DATE = '2012-09-04T13:45:59' / file creation date (YYYY-MM-DDThh:mm:ss UT)
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| − | END
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| − | | |
| − | where EFDD_VER and ICD_VER are the versions of the respective documents in which the structure is defined (dummy values in the example).
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| − | | |
| − | ==== EXTENSION 1: OBT ====
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| − | | |
| − | XTENSION= 'BINTABLE' / binary table extension
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| − | BITPIX = 8 / 8-bit bytes
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| − | NAXIS = 2 / 2-dimensional binary table
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| − | NAXIS1 = 9 / width of table in bytes
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| − | NAXIS2 = 15573106 / number of rows in table
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| − | PCOUNT = 0 / size of special data area
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| − | GCOUNT = 1 / one data group (required keyword)
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| − | TFIELDS = 2 / number of fields in each row
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| − | TTYPE1 = 'OBT ' / label for field 1
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| − | TFORM1 = '1K ' / data format of field: 8-byte INTEGER
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| − | TUNIT1 = '2**(-16)sec' / physical unit of field
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| − | TTYPE2 = 'Flag ' / label for field 2
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| − | TFORM2 = '1B ' / data format of field: BYTE
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| − | TUNIT2 = 'N/A ' / physical unit of field
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| − | EXTNAME = 'OBT ' / name of this binary table extension
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| − | TIMEZERO= '1660237181'
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| − | END
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| − |
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| − | | |
| − | where TIMEZERO is the value of the first timesample in the units of TUNIT1
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| − | | |
| − | ==== EXTENSION 2: 14_545_1_LFER4_JC_v51 ====
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| − | | |
| − | This is the first of the extensions containing the detector data, and is followed by more like it for the other detectors.
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| − | | |
| − | XTENSION= 'BINTABLE' / binary table extension
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| − | BITPIX = 8 / 8-bit bytes
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| − | NAXIS = 2 / 2-dimensional binary table
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| − | NAXIS1 = 5 / width of table in bytes
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| − | NAXIS2 = 15573106 / number of rows in table
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| − | PCOUNT = 0 / size of special data area
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| − | GCOUNT = 1 / one data group (required keyword)
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| − | TFIELDS = 2 / number of fields in each row
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| − | TTYPE1 = 'Signal ' / label for field 1
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| − | TFORM1 = '1E ' / data format of field: 4-byte REAL
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| − | TUNIT1 = 'KCMB ' / physical unit of field
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| − | TTYPE2 = 'Flag ' / label for field 2
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| − | TFORM2 = '1B ' / data format of field: BYTE
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| − | TUNIT2 = 'N/A ' / physical unit of field
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| − | EXTNAME = '14_545_1_LFER4_JC_v51' / name of this binary table extension
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| − | TIMEZERO= '1660237181'
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| − | CHANNEL = '545-1 '
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| − | END
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| − | | |
| − | Note that NAXIS must be the same for all extensions.
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| − | | |
| − | ''NB. may want to change EXTNAME to be just the detector name; the rest was for internal purposes only''
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| − | [[Category:Mission science products]] | |
