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systematics_wg_july_19_2017 [2017/07/19 11:11] – bcrillsystematics_wg_july_19_2017 [2017/07/19 11:47] (current) – bcrill
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 Agenda/Notes from Systematics WG telecon July 19 2017 Agenda/Notes from Systematics WG telecon July 19 2017
  
-on the call: Brendan, Paolo, Colin, Julian, Shaul+on the call: Brendan, Paolo, Colin, Julian, Shaul, Maurizio, Joy
  
   - S4 tools (Colin)   - S4 tools (Colin)
       * S4 doesn't yet have an instrument design, so at this point, they are considering generic "additive systematics" == something that adds additional B-mode power and could bias a measurment of "r"       * S4 doesn't yet have an instrument design, so at this point, they are considering generic "additive systematics" == something that adds additional B-mode power and could bias a measurment of "r"
       *  A generic noise-like systematic (not rolled off by beam) is considered       *  A generic noise-like systematic (not rolled off by beam) is considered
-      * Looked at an "uncorrelated" systematic (i.e. uncorrelated from band to band) such as residual beam mismatch+      * Looked at an "uncorrelated" systematic (i.e. uncorrelated from band to band) such as residual beam mismatch: a white and a 1/ell version 
 +      * Also looked at a correlated systematic which can bias cross-spectra, same amplitude (in CMB units) in all bands (i.e. looks like a CMB fluctuation) 
 +      * Going back to Fischer forecast, including foreground separation in frequency space: can write down what level of systematic corresponds to as a bias in "r" of 1e-4 (target of sigma_r in 5e-4) 
 +      * Colin is now applying this to the S4 data challenge.   
 +      * Longer term this is meant to provide a benchmark to judge systematics against as a real instrument design takes shape. 
 +      * What do we need in order to perform this type of analysis for the CMB probe Imager, given our set of bands and noise levels? 
 +        * Can be done just with map noise and frequency bands: though of course it assumes an analysis method  based on BICEP/Kick which may or may not be applicable to a full-sky analysis. 
 +        * Also noise shape for a full-sky mission is likely to be quite different.  Atmosphere enters in as an ell_knee 
 +        * Simple parameterization for foreground estimation: probably fine for ~3% sky, but for Probe would use a full-sky template fit. 
 +        * Julian points out that there will be a map-based analysis within S4 that will perhaps test this applicability.  The more pixels that are available for a full-sky map, a maximum likelihood starts to become computationally expensive.
   - Planck low ell polarization paper [[https://www.aanda.org/articles/aa/full_html/2016/12/aa28890-16/aa28890-16.html|Planck intermediate results XLVI. Reduction of large-scale systematic effects in HFI polarization maps and estimation of the reionization optical depth]] (Brendan)   - Planck low ell polarization paper [[https://www.aanda.org/articles/aa/full_html/2016/12/aa28890-16/aa28890-16.html|Planck intermediate results XLVI. Reduction of large-scale systematic effects in HFI polarization maps and estimation of the reionization optical depth]] (Brendan)
       * Summary plots       * Summary plots
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       * Specific plots       * Specific plots
         * Fig 2: noise PSDs and CSDs: correlated cosmic ray hits; Fig A.1 shows this propagated to TT/EE/BB residuals.         * Fig 2: noise PSDs and CSDs: correlated cosmic ray hits; Fig A.1 shows this propagated to TT/EE/BB residuals.
-        * Fig 4: far sidelobe pickup: propagated physical optics models.  (note: Physical optics models were not incredibly accurate)+        * Fig 4: HFI far sidelobe pickup: propagated physical optics models.  (note: Physical optics models were not incredibly accurate)
         * Fig 9: residual ADC nonlinearity with gain correction leaves low ell polarization residuals: see Fig B.13 for what it looks like on the sky         * Fig 9: residual ADC nonlinearity with gain correction leaves low ell polarization residuals: see Fig B.13 for what it looks like on the sky
         * Fig 10: "Empirical transfer function" unknown systematic         * Fig 10: "Empirical transfer function" unknown systematic
systematics_wg_july_19_2017.1500480676.txt.gz · Last modified: 2017/07/19 11:11 by bcrill

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