On the call: Eric, Brendan, Joy, Ranajoy, Maurizio, Jacques, Colin,

Agenda / Notes:

• Probe study purpose: inform NASA and 2020 Decadal Survey panel, show that excellent CMB science can be done for ⇐$1 Billion. charge to systematics WG should be that systematic errors do not dominate over science signals even without costly technology that drives us over the dollar limit.

• Big Picture look at the systematics list
• do we agree that the risk factor=5 items are really the riskiest effects? Did we miss anything?
• Items that got a 5 in SRF:
  • Sidelobes:Reflector spillover
  • Sidelobes: Stray reflections
  • Sidelobes: surface roughness
  • Beam ghosting
  • Scattering
  • Sidelobes: diffraction
  • Polarization Angle calibration: maybe rated too high? we do have the workaround that sacrifices the cosmic bifringence. No matter what, we should write down a calibration strategy
  • Gain stability: for CORE, looked at how well calibration could be done on the dipole, but not propagated to science errors. Should also look at ability to use CMB anisotropy to help with gain.
• Also note that beam mismatch leakage did not get a 5 but we must mention this for sure in the report, since it is a big issue that everyone thinks about, and perhaps other work can be cited to show that there are mitigations in analysis already available at the level we need.
• note that EVERY item on our list must be discussed, even just to argue that it's not a problem.
• will optical simulations be available for the baseline spacecraft/telescope design? probably shouldn't count on having super detailed GRASP level, but a fairly general systems model can be very powerful and won't be too wrong.
• action for Brendan to come up with simple model to cover most of the effects listed above.
• Maurizio would be happy to look into gain stability starting with the CORE setup, but he's busy with LSPE until December. He'd like to use TOAST to go a bit further.
• As far as estimating spectra from simulated maps in order to evaluate errors. Polspice is a good choice, works well on large sky patches, corrects for E/B leakage due to masking (not perfectly optimal, but probably good enough). Maybe need pixel-based codes for low-ell B? polspice probably good enough at looking at relative degradation for this type of systematics tests.
• action for Ranajoy to use existing tools to start from a CMB map, and look at effects of misaligned pol angles. Eric also suggests quickpol. can start w/ 16 detectors. Ranajoy can start on this in ~3 weeks.
• missing/needs volunteer: survey of beam leakage correction effects.