Legend: Bold face encodes 'need more information'; italics encodes issues that are (semi)settled in the sense that they are the basis for future discussions; Underlined Text are action items.

Telecon Notes by Al Kogut (with extra SH edits)

• Shaul has put an Excel spreadsheet onto the wiki executive area with bands used by previous imagers (concepts or flight missions). Need to look at previous literature on band optimization. Action: Will set up smaller working group to propose bands for Probe.
• List currently contains only bands from bolometer missions, not to be taken as dismissing lower frequencies.
• General agreement on wording of E-mail for community participation in working groups. Rafael to send brief description to Shaul for broader working group including non-inflationary fundamental physics (neutrino mass,

N_eff).

• Question for data challenge: What units should we use? Thermodynamic temperature units will pose a problem when trying to combine with channels above 1 THz from a spectrometer. Existing S4 material on disk is already in units mK thermodynamic temperature. Don't want to force massive rework, but don't want to prevent analysis of potential benefits from spectrometer data from higher frequencies. Action: Will sort offline with Julian/Clem.

Amy reviewed initial aperture analysis. Assume Falcon-9 launch vehicle, which has 4.6 m usable fairing diameter. Corresponding mirror effective aperture is 1.2 m to 1.4 m unless we go to deployables. Going to optics significantly larger than CoRE will require significant cost savings from some other subsystem. Is there a science driver (de-lensing?) that strongly pushes case for apertures significantly larger than 1.2 meters?

 o Action to contact Kris Gorski for trades on scan strategy
 o Can we distribute studies done for CoRE and LiteBIRD to Probe EC?

Cluster science: Adding space mission (CoRE) to ground_based (CMB-S4) significnantly enhances number of identified clusters. Driver is the improved foregrounds from space mission. See arXiv:1703.10456 for specific assumptions.

 o Action to review paper, see if this is worth looking into for Probe.