Attendance:

Notes by:

• Workshops (Raphael, Shaul)
• Status of Spectrometer decision (Al, Amy)
• Update from the Systematics WG (Brendan)
• Update from data challenge (Lloyd, Julian)

• Taken by Lloyd
• Foreground workshop dates are set to be Nov 29 to Dec 1. Location is UCSD.
• Science and complementarity workshop: JC proposed to keep S4 separate from an April/May Probe and decadal panel meeting. And have S4 in week of March 5 to 9. SH says that could work if we have a day or day and a half for complementarity. JC and S4 are going ahead looking at a 2-day or 2.5 day workshop, really focused on governance. JC still prefers a two separate workshop solution. Julian points out benefits to having these two workshops right next to each other, with some overlap. Chair selected by end of 2018. Julian and Lloyd to discuss at CMB-S4 ICCC meeting next week and report back.
• Spectrometer decision steps forward: Al needs to transfer to Amy an entire set of engineering specifications and cost estimates. Then Amy can provide downscope impacts for Imager. Then we figure out how Imager science is impacted. Then we can make our decision.
• Al has given engineering specifications to Amy, but is awaiting authority from GSFC to provide cost estimates. He and Amy are in communication. Amy is asking about the orientation of the spectrometer. She has looked at the technical information that they have (mass, power, data rate, thermal env. requirements, radiation tolerance, dimensions, moving parts, deployables, …) and they have not identified any immediate showstoppers or problems. what will take some time to investigate: the thermal needs and how do we accommodate them, and cost.
• SH: when we talk about descoping the imager, it's not so much the volume but the cost impact on what's left for the imager. What are the major cost-drivers of the spectrometer? Amy: we don't have a cost yet. It's not a small amount of money to pay for the spectrometer. We're not going to be able to pull that out of a single element of the imager. We have to imagine a much smaller imager if we have a spectrometer too. SH: when do you need the cost? now? within 2 weeks? I want to know what to convey to Al. AT: we're late at really getting into this. we've been talking about it for months. I'd like to get it as quickly as possible. We're not sitting on our hands yet. But it's important context for us. SH: if you get it today or tomorrow, when do you think you can come back to us and say 'here are the impacts' AT: Providing rough guidance could come pretty quickly. Some weeks before one can turn that into mirror sizes and number of detectors on the focal plane. About a month. We're driving to have the derivatives of cost wrt technical capability in place. SH: if we want to do this by around mid October. If you get the cost, is it realistic for us to say, within a week, e.g. spectrometer is $50M, and we can do it if imager is modified in this, roughly speaking, way. AT: yes, we can do a rough analysis like that in a week or two, and then continue to develop it.
• SH: we need the information probably by Monday. Then a few days afterwards we'll get together with Amy and Brian, and the next week give a rough sketch to the EC. Then in one more week get guidance from the EC. AT: sounds good.