Difference: HifiCalibrationWeb (107 vs. 108)

Revision 1082017-01-10 - DavidTeyssier

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META TOPICPARENT name="WebHome"

HIFI instrument and calibration web page

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  If your data have been processed with HIPE 13.0, HIPE 12.0 or HIPE 11.1

  • Intensity calibration uncertainty
Changed:
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    • HIPE 14 introduces a new product providing an estimated breakdown of the intensity calibration uncertainty. The uncertainties are given separately for each component, as well as in a quadratic sum fashion for all statistically independent elements. This sum applies to the calibration of data in the Ta* scale. Further systematic and random error apply for data converted into different intensity scales (e.g. Tmb or Jy). See further details in section 9 of the DRG.
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    • HIPE 14 introduces a new product providing an estimated breakdown of the intensity calibration uncertainty. The uncertainties are given separately for each component, as well as in a quadratic sum fashion for all statistically independent elements. This sum applies to the calibration of data in the Ta* scale. Further systematic and random errors apply for data converted into different intensity scales (e.g. Tmb or Jy). See further details in section 9 of the DRG.
 
  • Pointing reconstruction
    • In HIPE 14, those observations where the interlacing mode was activated (i.e. using more than just 9 guide stars in the star tracker) will benefit from an more accurate reconstructed astrometry and so positions may change in those cases. On top of that, the quality figure associated to the new gyro-propagated method introduced back in HIPE 13 (see also the following Pointing Information page) is now computed in a slightly different fashion. Since the application or not of the gyro-propagated pointing is, for HIFI, conditional upon a certain threshold on this quality (avoiding to apply the new pointing reconstruction to under-performing case), the number of case making us of one or the other approach will differ in HIPE 14 - we recall that in case the gyro-propagated method is discarded, the pointing is the same as that used back in HIPE 12.For the HIFI data such a correction is applied in a conditional fashion depending on a quality figure computed for each individual observation. The new pointing reconstruction will not apply to under-performing cases, and those latter will still use the pointing files used back in HIPE 12. Details about the new attitude reconstruction, and the way it is approached and may impact the HIFI data, can be found in this memo.
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    • In HIPE 14, a new channel flag has been introduced ("warning") that will be assigned to the data based on a knowledge base of spurious features built from the spectral scan flagging (see bullet above). These flags will be applied to all point and mapping observations. They should be taken as indicative as they not necessarily accurately match spurious features in the data where they got applied. For this reason, this new flag is not honoured by any of the standard interactive post-processing tasks.

  • Flags in OFF positions.
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    • In HIPE 13 the data used in the OFF positions were already processed up to an equivalent Level 2 calibration (both in intensity and frequency) in order to be directly comparable to the ON-target data. In HIPE 14, those OFF spectra will also hold spur and warning flags that will be propagated from the ON-targert ones. This feature is for example very interesting in order to perform a deconvolution of the OFF spectras in a spectral scan and be able to compare the OFF spectra to the level 2.5 deconvolved products of those observations.
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    • In HIPE 13 the data used in the OFF positions were already processed up to an equivalent Level 2 calibration (both in intensity and frequency) in order to be directly comparable to the ON-target data. In HIPE 14, those OFF spectra will also hold spur and warning flags that will be propagated from the ON-targert ones. This feature is for example very interesting in order to perform a deconvolution of the OFF spectra in a spectral scan and be able to compare the OFF spectra to the level 2.5 deconvolved products of those observations.
  If your data have been processed with a version earlier than 11.1

  • Solar System Object ephemerides
Changed:
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    • A bug (see here) was fixed in the calculation of SSO ephemeris positions (ra_centre/dec_centre) that led to offsets of up to ~10". This bug affected users that use cubes in a co-moving frame (including the standard Level 2.5 cubes), use the doOffset task, or make explicit use of ra_centre / dec_centre in their HIPE scripts. The offset is practically constant over a map and could, e.g., make the emission of a comet appear to be off-center when it really isn't. The fixed bug is in the Level 0 pipeline, which users cannot run easily. The issue was fixed in HIPE 11.1.
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    • A bug (see here) was fixed in the calculation of SSO ephemeris positions (ra_centre/dec_centre) that led to offsets of up to ~10". This bug affected users that use cubes in a co-moving frame (including the standard Level 2.5 cubes), use the doOffset task, or make explicit use of ra_centre / dec_centre in their HIPE scripts. The offset is practically constant over a map and could, e.g., make the emission of a comet appear to be off-center when it really isn't. The fixed bug is in the Level 0 pipeline, which users cannot run easily. The issue was fixed in HIPE 11.1.
  If your data have been processed with a version earlier than 10.3

  • DBS Observations If you have data processed with < HIPE 10
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Changed:
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  • This repository of system temperature plots across the IF for each HIFI subband (updated 24 Jan 2011) inform about the variation in system temperature (sensitivity) across the HIFI intermediate frequency band at various frequencies.
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  • This repository of system temperature plots across the IF for each HIFI subband (updated 24 Jan 2011) informs about the variation in system temperature (sensitivity) across the HIFI intermediate frequency band at various frequencies.
 

Calibration error budget

 
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