====== Telecon 20180516 ======

Attending: Brian, Tom, Kris, Hannes, Jacque, Shaul, Karl, Qi, 


Notes by : Qi

=== Agenda===

  * Precession Period (Kris, Jacques)
    * 10 hour precession period: {{:systematicswg:telecons:2018-05-14:orth_nobs_tprec10hrs_190_days.png?25|}} 
    * 48 hour precession period: {{:systematicswg:telecons:2018-05-14:orth_nobs_tprec48hrs_190_days.png?25|}}
    * {{::nobs_maps.pdf|More Slides}}
  *  {{::sensitivity_vs_frequency_20180516.pdf|Noise/Bands Figure}}
  * Noise Requirements vs Best Case Estimate (BCE)
    * Proposal: Req = BCE*rt(2)/0.9, independent of frequency
    * rt(2) because "Planck achieved noise within ~20% of BCE" (to be checked) 
    * 0.9 because the cost models assume 90% yield
    * first factor is applied on individual detectors, second factor on the array. 

===Notes===
  * Precession Period (Kris)
    * Shaul: we've debating whether fast or slow precession; Jacques's argument was too fast precessions give large gaps
    * high-resolution, 1.6 arcmin simulations, single detector
    * 10 hours vs 48 hours; 2,4,5,..., 365 days of scanning
    * blue (or gray on right side) is either 0 or just a few hits; yellow is a few hundred
    * short-time plots show difference, but long-time show less difference
    * Kris argues that either option is good at some locations; we need to specify science goals before we really answer this question. Also, since we are using action-wheels, we can fairly easily adjust precession in space. This is different from Planck. Planck did have some big gaps.
    * Jacque argues that we need to compare gap size with beam size. 48 hours comes from CORE study, which has 2-min spin rate and 96-hour precession.
    * conclusion: the report should probably say “there are a range of considerations, for either 10 or 48 hours”
    * Shaul: the fly-wheel will be able to do the change of precession; slow-motion can also be done.

  * Noise Requirements vs Best Case Estimate (BCE)
    * Best case estimate: not everything is most optimistic, just reasonable.
    * Shaul proposed BEC/sqrt(2)*0.9
      * root 2 is coming from Planck, which had achieved within 20% BCE.
      * 0.9 is 90% yield of pixels; BCE is optimistic on 100%-yield assumption
      * This number is for feedback loop to science teams.
      * Jacques: CORE did something similar, no major impacts on science

  * Noise/Bands Figure
    * goal: a standard visual
    * needs to clarify things, needs suggestions