Telecon 20171107

Attending: Brian, Julian, Al, Roger, Jeff, Jacques, Jon G.

Agenda:

• Preparations for TeamX in Dec.
  • Finalizing optics with/out deployables + focal system (Karl, Qi)
    • Comparing 1.2 m crossed and 1.4 m open (.pdf)
  • Telescope: material, alignment, testing
  • Cooling
• Mission
  • Scan angles (Gorski)
  • TM data rates [as a function of smallest beam size (??)]
• Systematics + noise
  • Combining our telecons with systematics group
    • impact of low frequency noise
    • Sidelobes (Grasp / Analytical calculation)
    • Gain stability
    • pol angle calibration

Prep for Team-X meeting in mid-Dec. They will cover telescope + focal plane + Cooling = instrument

1. Optics of 1.2m vs 1.4m. 1.4m open has better resolution and sensitivity.
   1. No glaring issues with open, even though it is less traditional.
   2. Brian: Does baffle create sidelobes?
      1. Shaul: Goal is to do a basic GRASP calculation to figure this out. In contact with Brad Johnson
   3. Karl will calculate sensitivity of crossed at 4K. Maybe something to pursue.
2. Should we go to Team-X with multiple options?
   1. Al: They tend to split their time evenly amongst options they are given. Would need to make clear what our focus is if we bring multiple options. Prefer taking just 1 workable option. It's time to finish with optics and move focus to other issues which need work.
      1. Shaul: Our case is 1 basic framework with options being changes on top of this.
      2. Al: Team-X can do this if the scope is made clear in pre-session. However may not be most effecient use of Team-X time/expertise.
3. Gathering telescope quotes:
   1. Brain, JPL, and Shaul.
   2. Components are fraction of cost. Majority of cost is testing.
      1. Al: WMAP testing was cold photograms, warm beams, accounted for cooling deformation with models
      2. Jacques: Planck testing was sidelobes warm, deformation and alignment as mirror cooled, no end-to-end cold test with flight system.
         1. CORE estimate, very unofficial, was $10-20 million
4. Cooling:
   1. Chris Payne working on strategy
   2. continuous ADR cost from Goddard slow to come in. Working on this.
   3. Possible single shot ADR from Europe. planned for Athena mission.
      1. Jacques: Same group is developing continuous ADR. Probably low TRL currently. Jacques willing to connect people if needed. (not needed currently)
   4. Roger: Will send around BLISS ADR system. Was a bench test system at JPL.

Skip Mission discussion for now, deadline in March although work needs to begin.

Systematics

1. What do we need for 1/f? Sidelobes? Gain stability? pol angle calibration? And how to simulate this.
2. Sidelobes: Estimate in GRASP via Brad J.
   1. Jacques: This job is very large and approximations are often done.
   2. Shaul: Plan is to do a course model to get representative levels.
3. Julian: Simulation pipelines exist to take scan + sidelobes, produce maps, and estimate systematic errors in parameters.
   1. need proper inputs
   2. simulation of mitigation of sidelobes is harder. Need a way to estimate your sidelobes and your mitigation method separately, then combine in simulation.
   3. typically simulate each systematic separately, then do 1 sim with all systematics to see overall effects.
      1. Shaul: this can get infinitely complex. We'll focus on the 3 issues highlited by systematics group first.
   4. All these are doable, suggestion: Do 4-5 locations on focal plane.
      1. Jacques: do 4 detectors simultaneously so you get 1 Q and 1 U measurement.