Difference between revisions of "Map-making"

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(SRoll scheme)
(SRoll scheme)
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* the absolute calibration from the orbital dipole which does not project on the sky.
 
* the absolute calibration from the orbital dipole which does not project on the sky.
  
The destripper is only sensitive to differences between bolometer coefficients. The absolute value of the parameters is taken keeping the average of all detectors in a frequency band imposing:
+
The destripper is only sensitive to differences between bolometer coefficients. The absolute average value of the parameters within a frequency band is taken imposing:
 
* the sum of the offsets to be zero (no monopoles),
 
* the sum of the offsets to be zero (no monopoles),
 
* the average of the additional color corrections (for both dust and free-free emission) to be zero, thus keeping the same average as the one measured on the ground.
 
* the average of the additional color corrections (for both dust and free-free emission) to be zero, thus keeping the same average as the one measured on the ground.

Revision as of 13:24, 24 May 2018

Introduction[edit]

This section gives an overview of the mapmaking and the calibration procedures used to build the HFI maps.

  • Procedures for the 2013 release is to be found in Planck-2013-VI[1] and Planck-2013-VIII[2] (see at the bottom of this page)
  • Procedures for the 2015 release is to be found in Planck-2015-A08[3] (see at the bottom of this page)
  • In 2016, a new procedure called SRoll has been introduced to extract, from the sky, parameters for systematics important to the mapmapking. This is achieved through a generalized polarized destripper which uses the redundancy between detectors inside a frequency band. Systematic effects producing leakages from intensity to polarization contribute strongly to this determinations. This allowed for the first time the use of large scale polarized data and the extraction of the reionization parameter. The procedure and its results are described in Planck-2016-XLVI[4].
  • For the 2018 legacy release, the same SRoll procedure has been used to produce the frequency intensity and polarization maps. Planck-2020-A3[5] fully describes the procedures, the products and their characterization.

SRoll global solution[edit]

Inputs to the mapmaking[edit]

For the 2017 release, the TOI processing remains unchanged from the previous 2015 release (see http://wiki.cosmos.esa.int/planckpla-int/index.php/TOI_processing). As mentionned in TOI proc page (LVLV), a small cut of in the data selection (1000 pointing periods) has been done at the end of the cryogenic mission.

SRoll scheme[edit]

SRoll makes use of an extended destriper. Destriper method have been used previously to remove baseline drifts from detector time streams, while making co-added maps of the data, by taking advantage of the redundancy in the scanning strategy. \sroll\ is a generalized polarized destriper which, in addition, compares all the observations of the same sky pixel by the same detector with different polarization angles, as well as by different detectors within the same frequency band. This destriper thus fits differences between instrument parameters that minimize the difference between all polarized observations of the same sky pixel in the same frequency band. SRoll solves consistently for:

  • one offset for each pointing period,
  • an empirical transfer function adding to the correction already done in the TOI processing (time constants less than 3 seconds), covering time constants up to 30 seconds,
  • a CMB calibration mismatch between detectors, detected through the shift on the total kinetic dipole, between odd and even surveys, inducing leakage from intensity to polarization,
  • a bandpass mismatch for foregrounds response due to color corrections with respect to the CMB calibration, also inducing leakage from intensity to polarization. This makes use of an input spatial template (2015 Planck component separation results) of each foreground,
  • the absolute calibration from the orbital dipole which does not project on the sky.

The destripper is only sensitive to differences between bolometer coefficients. The absolute average value of the parameters within a frequency band is taken imposing:

  • the sum of the offsets to be zero (no monopoles),
  • the average of the additional color corrections (for both dust and free-free emission) to be zero, thus keeping the same average as the one measured on the ground.

Products[edit]

Healpix Pixel Rings (HPRs)[edit]

SRoll main products are the HFI frequency maps. Nevertheless, we also make available the Healpix Pixel Rings (HPRs) of those maps, ie. the data before projection. See description of those file HERE. LVLV refer to the PLA URL

Frequency maps[edit]

The 35 HFI frequency maps of the 2017 Legacy Release are the followings:

2017 HFI frequency maps
100 GHz 143 GHz 217 GHz 353 GHz 353_PSB GHz 545 GHz 857 GHz
Full mission I, Q, U I, Q, U I, Q, U I, Q, U I, Q, U I I
Half mission 1 I, Q, U I, Q, U I, Q, U I, Q, U I, Q, U I I
Half mission 2 I, Q, U I, Q, U I, Q, U I, Q, U I, Q, U I I
Odd rings I, Q, U I, Q, U I, Q, U I, Q, U I, Q, U I I
Even rings I, Q, U I, Q, U I, Q, U I, Q, U I, Q, U I I

See description of those files HERE. LVLV: refer to the PLA URL

Sub-pixel effect in very bright regions[edit]

The bandpass corrections have been optimized for high latitude regions which implied to reduce the noise of the CO and dust bandpass templates to avoid the introduction of significant correlated noise. The effect is negligible for dust but not for CO in very bright regions. See detailled description HERE.

Complementary figures of the HFI 2018 DPC paper[edit]

Complementary figures of the HFI 2018 DPC paper ( Planck-2020-A3[5]) are given HERE.

Previous Releases: (2015) and (2013) Mapmaking and photometric calibration[edit]

Expand

2015 Mapmaking and photometric calibration

Expand

2013 Mapmaking and photometric calibration

References[edit]

  1. Jump up to: 1.01.11.21.31.41.5 Planck 2013 results. VI. High Frequency Instrument Data Processing, Planck Collaboration, 2014, A&A, 571, A6.
  2. Jump up to: 2.02.12.2 Planck 2013 results. VIII. HFI photometric calibration and Map-making, Planck Collaboration, 2014, A&A, 571, A8.
  3. Jump up to: 3.03.13.23.33.43.5 Planck 2015 results. VIII. High Frequency Instrument data processing: Calibration and maps, Planck Collaboration, 2016, A&A, 594, A8.
  4. Jump up Planck intermediate results. XLVI. Reduction of large-scale systematic effects in HFI polarization maps and estimation of the reionization optical depth, Planck Collaboration Int. XLVI A&A, 596, A107, (2016).
  5. Jump up to: 5.05.1 Planck 2018 results. III. High Frequency Instrument data processing and frequency maps, Planck Collaboration, 2020, A&A, 641, A3.
  6. Jump up to: 6.06.1 Planck 2013 results. XIII. Galactic CO emission, Planck Collaboration, 2014, A&A, 571, A13.
  7. Jump up to: 7.07.17.2 Planck 2015 results. X. Diffuse component separation: Foreground maps, Planck Collaboration, 2016, A&A, 594, A10.
  8. Jump up Planck 2015 results. VII. High Frequency Instrument data processing: Time-ordered information and beam processing, Planck Collaboration, 2016, A&A, 594, A7.
  9. Jump up Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results, G. Hinshaw, J. L. Weiland, R. S. Hill, N. Odegard, D. Larson, C. L. Bennett, J. Dunkley, B. Gold, M. R. Greason, N. Jarosik, E. Komatsu, M. R. Nolta, L. Page, D. N. Spergel, E. Wollack, M. Halpern, A. Kogut, M. Limon, S. S. Meyer, G. S. Tucker, E. L. Wright, ApJS, 180, 225-245, (2009).
  10. Jump up Planck 2013 results. XV. CMB power spectra and likelihood, Planck Collaboration, 2014, A&A, 571, A15.
  11. Jump up Planck 2013 results. XXXI. Consistency of Planck data, Planck Collaboration, 2014, A&A, 571, A31.

(Planck) High Frequency Instrument

Cosmic Microwave background

Planck Legacy Archive

Data Processing Center

(Hierarchical Equal Area isoLatitude Pixelation of a sphere, <ref name="Template:Gorski2005">HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the Sphere, K. M. Górski, E. Hivon, A. J. Banday, B. D. Wandelt, F. K. Hansen, M. Reinecke, M. Bartelmann, ApJ, 622, 759-771, (2005).

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Noise Equivalent Power

Full-Width-at-Half-Maximum

reduced IMO

Planck Sky Model