Difference between revisions of "HFI-Validation"

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{{DISPLAYTITLE:Internal overall validation}}
 
{{DISPLAYTITLE:Internal overall validation}}
 
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The HFI validation is mostly modular. That is, each part of the pipeline, be it timeline processing, map-making, or any other, validates the results of its work at each step of the processing, looking specifically for known issues. In addition, we do additional validation with an eye towards overall system integrity by looking at generic differences between sets of maps, in which most problems will become apparent, whether known or not. Both these are described below.  
 
The HFI validation is mostly modular. That is, each part of the pipeline, be it timeline processing, map-making, or any other, validates the results of its work at each step of the processing, looking specifically for known issues. In addition, we do additional validation with an eye towards overall system integrity by looking at generic differences between sets of maps, in which most problems will become apparent, whether known or not. Both these are described below.  
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* Bandpass - The transmission curves, or "bandpass" has shown up in a number of places. This is discussed in {{PlanckPapers|planck2013-p03d|1|the 2013 spectral response paper}}.  
 
* Bandpass - The transmission curves, or "bandpass" has shown up in a number of places. This is discussed in {{PlanckPapers|planck2013-p03d|1|the 2013 spectral response paper}}.  
 
* Saturation - While this is mostly an issue only for Jupiter observations, it should be remembered that the HFI detectors cannot observe arbitrarily bright objects. This is discussed in [[#Saturation|the section below on saturation]].
 
* Saturation - While this is mostly an issue only for Jupiter observations, it should be remembered that the HFI detectors cannot observe arbitrarily bright objects. This is discussed in [[#Saturation|the section below on saturation]].
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==Generic approach to systematics==
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==Generic approach to systematics==
 
  
 
While we track and try to limit the individual effects listed above, and we do not believe there are other large effects which might compromise the data, we test this using a suite of general difference tests. As an example, the first and second years of Planck observations used almost exactly the same scanning pattern (they differed by one arc-minute at the Ecliptic plane). By differencing them, the fixed sky signal is almost completely removed, and we are left with only time variable signals, such as any gain variations and, of course, the statistical noise.  
 
While we track and try to limit the individual effects listed above, and we do not believe there are other large effects which might compromise the data, we test this using a suite of general difference tests. As an example, the first and second years of Planck observations used almost exactly the same scanning pattern (they differed by one arc-minute at the Ecliptic plane). By differencing them, the fixed sky signal is almost completely removed, and we are left with only time variable signals, such as any gain variations and, of course, the statistical noise.  

Revision as of 16:48, 29 January 2015


The HFI validation is mostly modular. That is, each part of the pipeline, be it timeline processing, map-making, or any other, validates the results of its work at each step of the processing, looking specifically for known issues. In addition, we do additional validation with an eye towards overall system integrity by looking at generic differences between sets of maps, in which most problems will become apparent, whether known or not. Both these are described below.

Expected systematics and tests (bottom-up approach)[edit]

Like all experiments, Planck/HFI had a number of "issues" which it needed to track and verify were not compromising the data. While these are discussed in appropriate sections, here we gather them together to give brief summaries of the issues and refer the reader to the appropriate section for more details.

Generic approach to systematics[edit]

This Page is Under Construction


References[edit]

(Planck) High Frequency Instrument

random telegraphic signal

Cosmic Microwave background

[LFI meaning]: absolute calibration refers to the 0th order calibration for each channel, 1 single number, while the relative calibration refers to the component of the calibration that varies pointing period by pointing period.

analog to digital converter