systematicswg:telecons:2018-02-21:start [Probe Mission Study Wiki]

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On todays' call: Brendan, Ranajoy, Eric, Maurizio, Shaul, Karl, Joy

=== Pointing Errors and Effect on B-modes ===

  * See Matias' memo made for EBEX {{:systematicswg:telecons:2018-02-21:matias-sam_pointing_20060918.pdf| Memo from 2006}}, based on "Benchmark Parameters for CMB Polarization Experiments"
  * Imagine a final pointing error per pixel at the level of the map (individual sampling pointing error can be larger provided they are small enough that E and B are linear over the error range, and hence the error on E and B averages down as the pointing error averages down for repeated hits)
  * B-modes get created from E-modes from this pointing error, in a way completely analogous to lensing
  * With a first order Taylor development on Q and U as a function of pointing error (Q(theta + dtheta) = Q(theta) + dtheta dQ/dtheta), you can analytically calculate the spurious B-modes coming from a pointing error power spectrum for a given E-mode ps
  * To make the calculation, we assume the pointing error power spectrum is white with a cutoff scale \ell_s (i.e. no pointing errors on scales smaller than \ell_s, pointing ps dies down at \ell > \ell_s)
  * With 8' beam, worse case for pointing error is \ell_s is 500, in which case spurious B-modes constitute 1/10th of primordial B-modes at \ell=100 if:
    * T/S=1e-4: sigma_theta = 1.2"
    * T/S=1e-5: sigma_theta = 0.4"
  * Note that previously for larger T/S, the tighest constraint on pointing came from not affecting lensing B-modes at \ell=1000.
  * Ranajoy and Eric to look into T to B leakage effects,which may enter in here given that there is no half-wave plate.
    * See [[:pointing_error_1|Note by Eric]]

=== Other Progress Updates ===
  * GRASP sims {{:systematicswg:telecons:2018-02-14:grasp_status_20180214.pdf|status slides}}
     * Karl is running GRASP at 1 degree resolution for FSL calculations, it agrees well with Brad's higher resolution runs. 
     * A non-physical feature related to the stop between the primary and secondary is being investigated
     * In the meantime, Karl is taking with Julian to test interfaces: he will start with a simple empirical fit to the known physical FSL feature and attempt to plug it into toast tools.
     * Brendan to try to connect Karl to GRASP experts.
  * Gain mismatch
      * Good progress! A 40-day simulation that will allow shakeout of Maurizio's code is underway as we speak.  Once that is done, the full mission sim can proceed.  
  * Polarization Angle Calibration
    * {{:systematicswg:telecons:2018-02-21:matias_cross-pol_20060709.pdf|Matias' Cross Pol memo}}
    * Ranajoy to investigate requirement
  * Systematics Memo Outline
    * Send Brendan feedback offline
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