Difference between revisions of "HFI-Validation"

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(Expected systematics and tests (bottom-up approach))
(Expected systematics and tests (bottom-up approach))
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* Cosmic Rays - Unprotected by the atmosphere and more sensitive than previous bolometric experiments, HFI saw many more cosmic ray hits than previous experiments. These were detected, the worst parts of the data flagged as unusable, and "tails" were modeled and removed. This is described in [[TOI_processing#Glitch_statistics|the section on glitch statistics]]<!-- and in [[#Cosmic_rays|the section on cosmic rays]],--> as well as in {{PlanckPapers|planck2013-p03e|1|the 2013 HFI Cosmic Ray Removal paper}}.
 
* Cosmic Rays - Unprotected by the atmosphere and more sensitive than previous bolometric experiments, HFI saw many more cosmic ray hits than previous experiments. These were detected, the worst parts of the data flagged as unusable, and "tails" were modeled and removed. This is described in [[TOI_processing#Glitch_statistics|the section on glitch statistics]]<!-- and in [[#Cosmic_rays|the section on cosmic rays]],--> as well as in {{PlanckPapers|planck2013-p03e|1|the 2013 HFI Cosmic Ray Removal paper}}.
 
* Elephants - Cosmic rays also hit the HFI 100 mK stage and cause the temperature to vary, inducing small temperature and thus noise variations in the detectors. These are removed with the rest of the thermal fluctuations, described directly below.  
 
* Elephants - Cosmic rays also hit the HFI 100 mK stage and cause the temperature to vary, inducing small temperature and thus noise variations in the detectors. These are removed with the rest of the thermal fluctuations, described directly below.  
* Thermal Fluctuations - HFI is an extremely stable instrument, but there are small thermal fluctuations. These are discussed in [[TOI_processing#Thermal_template_for_decorrelation|the timeline processing section on thermal decorrelation]] and in [[#1.6K_and_4K_stage_fluctuations|the section on 1.6 K and 4 K thermal fluctuations]].
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* Thermal Fluctuations - HFI is an extremely stable instrument, but there are small thermal fluctuations. These are discussed in [[TOI_processing#Thermal_template_for_decorrelation|the timeline processing section on thermal decorrelation]]<!-- and in [[#1.6K_and_4K_stage_fluctuations|the section on 1.6 K and 4 K thermal fluctuations]]-->.
 
* Random Telegraphic Signal (RTS) or Popcorn Noise - Some channels were occasionally affected by what seems to be a baseline which abruptly changes between two levels, which has been variously called popcorn noise or random telegraphic signal. These data are usually flagged. This is described in [[TOI_processing#Noise_stationarity|the section on noise stationarity]] and [[#RTS_noise|the section on Random Telegraphic Signal Noise]]
 
* Random Telegraphic Signal (RTS) or Popcorn Noise - Some channels were occasionally affected by what seems to be a baseline which abruptly changes between two levels, which has been variously called popcorn noise or random telegraphic signal. These data are usually flagged. This is described in [[TOI_processing#Noise_stationarity|the section on noise stationarity]] and [[#RTS_noise|the section on Random Telegraphic Signal Noise]]
 
* Jumps - Similar to but distinct from popcorn noise, small jumps were occasionally found in the data streams. These data are usually corrected. This is described in [[TOI_processing#jump_correction|the section on jump corrections]].  
 
* Jumps - Similar to but distinct from popcorn noise, small jumps were occasionally found in the data streams. These data are usually corrected. This is described in [[TOI_processing#jump_correction|the section on jump corrections]].  

Revision as of 16:58, 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 section 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