Difference between revisions of "HFI performance summary"

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[[Category:The satellite|0027]]
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The HFI operated flawlessly for 30 months, the maximum autonomy expected for the helium of the dilution cooler. The telescope pointing was achieved with an accuracy better than expected and reconstructed to a few seconds of arc. Fifty of the 52 bolometers collected data in very stable conditions during the whole mission, and practically all of the data were correctly recorded.
  
The essential characteristics of the HFI are gathered in the table below. The HFI has been operating flawlessly for 30 months, the most optimistic expected duration of the helium used by the dilution cooler. [The telescope pointing was achieved with an accuracy of a few arc-seconds. All of the fifty-two bolometers -but two- collected data in very stable conditions during the whole mission, and practically all of the data was correctly recorded.]
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The essential characteristics of the HFI are gathered in the table below. The extreme sensitivity provided by the 100 mK bolometers and the HFI architecture provided a new view of the submillimetre and millimetre sky, with a noise level not far from the fundamental limits set by the photon noise of the observed source. However, expected and unexpected systematic effects were seen, the most noticeable of them being the spikes in the signal produced by cosmic rays hitting the bolometers and their immediate surroundings. The sensitivity here is obtained from the half difference of the half rings. The overall sensitivity for the 2013 release was around that announced as the goal in the [http://www.sciops.esa.int/SA/PLANCK/docs/Bluebook-ESA-SCI(2005)1_V2.pdf|"bluebook"] {{BibCite|planck2005-bluebook}} , i.e. 2 times better than the required sensitivity. These numbers improved by about √2 when the whole mission data become available.
 
 
Systematics are now measurable, the most apparent of which being the spikes in the signal produced by cosmic rays hitting the bolometers and their immediate surrounding. [Minute ADC non-linearity revealed by the data scrutiny is being corrected.]
 
 
 
The extreme sensitivity provided by the 100 mK bolometers and the HFI architecture has provided a view of the submillimetre sky with a noise not far from the fundamental limits set by the photon noise of the observed source. In the same time,  The overall sensitivity is finally around that announced as the goal in the "bluebook" <cite>#Planck2005-bluebook<\cite>, i.e. twice better than the required sensitivity. One can expect to improve these numbers by about root two when the whole mission data is available.
 
  
 
{| class="wikitable" border="1" cellpadding="3" cellspacing="0" align="center" style="text-align:left"
 
{| class="wikitable" border="1" cellpadding="3" cellspacing="0" align="center" style="text-align:left"
|+ '''Beam size and sensitivity for the nominal mission (15 months)'''
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|+ '''Beam size and sensitivity of maps for the nominal mission (15 months)'''
 
|-
 
|-
 
|'''Frequency'''
 
|'''Frequency'''
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|857 GHz  
 
|857 GHz  
 
|-
 
|-
|'''Beam size (FWHM, arcmin)'''
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|'''Beam size [FWHM, arcmin]'''
 
|9.66
 
|9.66
 
|7.27
 
|7.27
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|4.58  µK/K
 
|4.58  µK/K
 
|15.17  µK/K
 
|15.17  µK/K
|0.013 Mjy/sr
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|0.013 MJy sr<sup>-1</sup> (*)
|0.013 Mjy/sr
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|0.013 MJy sr<sup>-1</sup> (*)
 
|-
 
|-
 
|'''Goal sensitivity'''
 
|'''Goal sensitivity'''
|2.5  
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|2.5 µK/K
|2.2  
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|2.2 µK/K
|4.8  
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|4.8 µK/K
|14.7  
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|14.7 µK/K
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|0.023 MJy sr<sup>-1</sup>
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|0.041 MJy sr<sup>-1</sup>
 
|}
 
|}
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 +
(*) These sensitivities are only valid for high Galactic latitude.
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==references==
 
==references==
<biblio force=false>
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<References />
#[[References]]
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<\biblio>
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[[Category:HFI design, qualification and performance|005]]

Latest revision as of 06:48, 10 December 2014

The HFI operated flawlessly for 30 months, the maximum autonomy expected for the helium of the dilution cooler. The telescope pointing was achieved with an accuracy better than expected and reconstructed to a few seconds of arc. Fifty of the 52 bolometers collected data in very stable conditions during the whole mission, and practically all of the data were correctly recorded.

The essential characteristics of the HFI are gathered in the table below. The extreme sensitivity provided by the 100 mK bolometers and the HFI architecture provided a new view of the submillimetre and millimetre sky, with a noise level not far from the fundamental limits set by the photon noise of the observed source. However, expected and unexpected systematic effects were seen, the most noticeable of them being the spikes in the signal produced by cosmic rays hitting the bolometers and their immediate surroundings. The sensitivity here is obtained from the half difference of the half rings. The overall sensitivity for the 2013 release was around that announced as the goal in the "bluebook" [1] , i.e. 2 times better than the required sensitivity. These numbers improved by about √2 when the whole mission data become available.

Beam size and sensitivity of maps for the nominal mission (15 months)
Frequency 100 GHz 143 GHz 217 GHz 353 GHz 545 GHz 857 GHz
Beam size [FWHM, arcmin] 9.66 7.27 5.01 4.86 4.84 4.63
Sensitivity per fiducial pixel 3.95 µK/K 2.35 µK/K 4.58 µK/K 15.17 µK/K 0.013 MJy sr-1 (*) 0.013 MJy sr-1 (*)
Goal sensitivity 2.5 µK/K 2.2 µK/K 4.8 µK/K 14.7 µK/K 0.023 MJy sr-1 0.041 MJy sr-1

(*) These sensitivities are only valid for high Galactic latitude.

references[edit]

  1. The Scientific Programme of Planck, Planck Collaboration, ESA publication ESA-SCI(2005)/01, (2005).

(Planck) High Frequency Instrument

Full-Width-at-Half-Maximum

European Space Agency