Difference: PacsCalibrationWeb (156 vs. 157)

Revision 1572017-03-27 - KatrinaExter

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META TOPICPARENT name="WebHome"

PACS instrument and calibration web pages

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        • chop nod (Telescope background normalisation): 5% up to 150 μm, and 10% beyond
        • unchopped (calBlock + RSRF): 10% for all wavelengths
  • An explanation of the data errors for any particular observation is provided in the PACS Data Reduction Guide for spectroscopy (sec. 7.6)
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  • PACS spectrometer beams: The PACS spectrometer beam efficiencies are maps of the response of each detectors on the sky. They describe the (relative) coupling of a point source to each spaxel as a function of its (the source) position in the FOV.
    • Version 6, the most up-to-date, can be directly downloaded in a tar ball PCalSpectrometer_Beam_v6.tar.gz. The corresponding calibration files are named BeamsPerSpaxelXXX, depending on the band.
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  • PACS spectrometer beams: The PACS spectrometer beam efficiencies are maps of the response of each detector on the sky. They describe the (relative) coupling of a point source to each spaxel as a function of its (the source) position in the FOV.
    • Version 6, the most up-to-date, can be directly downloaded as a tar ball PCalSpectrometer_Beam_v6.tar.gz. The calibration files are named BeamsPerSpaxelXXX, depending on the [XXX] band.
 
    • The PACS beam efficiencies are based on Neptune raster maps at certain (14) wavelengths observed during the mission:
      • Coarse 25x25 raster maps with raster step size 2.5" were obtained between ODs 174 and 751 in chopped mode covering all 25 spaxels.
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      • Fine Neptune 5x5 raster maps with raster step size 2 were executed on ODs 1311 and 1312. The combination of four such fine rasters, offset by 1", provide very high sampling for the central spaxel beam efficiency only.
      • All these measurements were registered using least squares minimization in coordinates and gain, and a synthetic beam was constructed with the coarse raster outside the area covered by fine raster and from matched fine raster inside. Finally, this synthetic beam is interpolated into a 0.5" grid.
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      • Fine Neptune 5x5 raster maps with raster step size 2 were executed on ODs 1311 and 1312. The combination of four such fine rasters, offset by 1", provide very high sampling but for the central spaxel beam efficiency only.
      • All these measurements were registered using least squares minimisation in coordinates and gain, and a synthetic beam was constructed with the coarse raster outside the area covered by fine raster and from matched fine raster inside. Finally, this synthetic beam is interpolated into a 0.5" grid.
 
      • All raster maps were observed with only one chop -off position (aka, asymmetric chopNod).
    • Beam efficiencies are normalised so that a point source of flux 1 at the centre of spaxel 12 has an integral of the instrument response equal to 1.
    • The WCS associated with the beam is in sky coordinates for position angle 0.
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    • A full history of the PACS Spectrometer beam efficiencies versions can be found in PACSSBeamEfficienciesControlVersion.pdf
    • The raw data from which the PACS spectrometer beams (all versions) have been derived is also available as tables (y, z offset - signal):
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    • A full history of the PACS spectrometer beam efficiencies versions can be found in PACSSBeamEfficienciesControlVersion.pdf
    • The raw data from which the PACS spectrometer beams (all versions) were derived are also available as tables (y, z offset - signal):
 
      • SpecSpatial_BeamEfficiency_central_spaxel_tables_v1.tar.gz:This contains a FITS file for each wavelength measured for the central spaxel only. Raw data of the coarse and fine rasters are combined. The array dimension of the fits file is [3,npoints] where the first column gives the y raster position, the 2nd column the z raster position and the 3rd column the normalised flux measured at this raster position.
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      • SpecSpatial_BeamEfficiency_tables_v1.tar.gz: Raw measurements PACS beams - all spaxels, coarse raster measurements only: each fits files corresponds to one wavelength. Each file contains the data for all spaxels of the coarse raster measurement only. Each fits file holds an array of 3x25x25x25 where: (0,25,25,25)=y raster position, (1,25,25,25)=z raster position, (2,25,25,25)=flux normalized to the central spaxel. The second and third dimensions are the raster position indices (y and z) and the last dimension is the module number (=spaxel number).
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      • SpecSpatial_BeamEfficiency_tables_v1.tar.gz: Raw measurements PACS beams - all spaxels, coarse raster measurements only: each fits files corresponds to one wavelength. Each file contains the data for all spaxels of the coarse raster measurement only. Each fits file holds an array of 3x25x25x25 where: (0,25,25,25)=y raster position, (1,25,25,25)=z raster position, (2,25,25,25)=flux normalised to the central spaxel. The second and third dimensions are the raster position indices (y and z) and the last dimension is the module number (=spaxel number).
 

PACS calibration file versions

  • When starting HIPE, you will be informed if new calibration files are available. Clicking on show details will show you the release note of the new calibration set, with details about the changes. This is further explained in the PDRGs. Clicking on Install will install the latest calibration files.
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Standard Products

The Herschel Science Archive provides bulk-processed Level 2/2.5 products for photometry and spectroscopy.

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  • All observations will be processed to Level 2. The pointed chop-nod observations for which the full SED is covered by 2 (or more) observations will also have a Level 3 (see for a list of these observations). The unchopped range scan on-source observations for which an off-source observation was requested will have a Level 2.5 that contains the background-subtracted results (see for a list of these observations, and the associated off-source obsid for any on-source obsid is given in the comments in the qualitySummary).
  • For some observations, one of the cameras (red or blue) may not have processed all the way to the final level due to data being out of the filter band borders: this is normal and a comment in the qualitySummary should say exactly that. Some observations will have failed in one camera but not another due to instrumental anomalies: again, a comment in the qualitySummary will explain what has happened.
 
  • This Data Processing Known Issues page describes typical problems and caveats the observer needs to be familiar when looking at the results of this "SPG" (standard product generation) processing. Aspects of product quality which can be further optimised by interactive processing are also summarised here. The document refers to the version of data processing pipeline currently being used for processing of incoming Herschel data.
  • For a explanation of PACS products, i.e. what you get when you download a complete or part of an observation from the HSA, see the Info PACS Products Explained, which can also be found on the HIPE help pages.
  • PACS data are reduced with pipeline scripts which are a set of command-line tasks that process the data from Level 0 (raw) to Level 2/2.5 (science-ready). There is more than one flavour of pipeline script, tailored to different types of science target, AOT, and observing plan. These 'interactive' pipeline scripts are provided in HIPE and explained in the data reduction guides.
 
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