Minutes of ANASAC Telecon Feb 24, 2020

Attendees: Giles, Kate, Dan, Jin, Chris, Shih-Ping, Stephen, Crystal, Al, Phil

zoom connection problem, delayed the meeting by 15 min.

1. ASAC is working on new "Principles of Review" and can summarize likely changes.

Chris: Stephen submitted a list of suggestion/comments last Friday to John C who will share the revised document before ASAC f2f meeting. Various types of comments, some discussion about DDT (how to use the it for large programs); nothing major.

Giles: can we see the results from the Survey for DPR? ANASAC would like to see the document.

Stephen: ASAC has a document, but not allowed to share at this point. The result is encouraging as interpreted by JAO: even split between against, in favor, or neutral; JAO thinks it’s not rejected, so the current stage is to implement this on the main call (small proposals only).

2. EOC priorities

Stephen: ASAC is asked to review/prioritize the commissioning task plan beyond cycle 9. John C will have a revised plan, available before the ASAC meeting. Basically, the observatory wants to know the high priority for the next 4-yr commission plans.

Recommendation: extending the frequency range in polarization mode

Giles: motivated by dust scattering in mm; high-frequency polarization mode should be high priority.

Crystal: This is in the top priority, and just needs good weather for commissioning this mode in high frequency. No particular problem.

Stephen: how about calibrators?

Crystal: this is not just for polarization mode, it’s an issue for all high frequency observations. The issue is only for ACA stand-alone mode because the pipeline is not ready for this stand-alone mode. If this is desirable, the priority can be moved up. How high frequency we consider this should be done?

Al: Band 8 polarization performance is poor.

Giles: We should push for Band 9. Having any higher frequency higher than the current available is useful.

SP: I would prefer lower frequency. Band 1 will be great (VLA can do this).

Recommendation: extended baseline by combining all available arrays (7+12)

Jin: How about extended baseline, with combining all available arrays (7+12)?

Crystal: Some early study on this capability shows some improvement, but not improved significantly. Current plan is to have CASA have the capability to do calibrations of such observations first, and then figure out the best configuration. Proper imaging not yet implemented.

Crystal: For proposal process, this could create problems (how to only select point source proposals for this mode). Many other issues identified, the gain for this step is not that high.

Stephen: Solar observation is fine, and the issue is mostly pipeline problem.

Crystal: pipeline can handle this. Two years ago, this has been full validated (7+12). Proper imaging is the problem. [Al notes: There is a collection of notes on the use of the ACA, the ACA Full Array, and the Combined Array at: https://safe.nrao.edu/wiki/bin/view/ALMA/CalAca]

Stephen: for the next four years, we should make sure this capability (current array configurations) is implemented. Agreed.

3. single-dish continuum

Recommendation: the gain in improving the continuum sensitivity in the total power mode is not worth the effort that needs to be put in.

Stephen: What should be done for the poor continuum sensitivity (four times worse because the receivers are just not stable enough) in the total power mode. What’s the science driven/can only be done by this mode? For Sun, this is not an issue. The question is whether this mode should be offered (besides the Sun)? If so, a clear justify is needed in the proposal that the performance can be done in the reasonable time.

Chris: It seems not worth doing, judging from a comparison of the sensitivity (42 mJy/beam in the provided document) vs. what can be done with JCMT/SCUBA2, 4 mJy/beam, which is 20 times better. So, it seems that only some special cases should be allowed (the Sun, and maybe some planets), and other cases can be submitted through DDT.

Crystal: Additional cost seems not justified at present (e.g., for OT development). Significant resources were already sunk into doing the report.

Stephen: might be improved by a factor of 2, but require new stuff installed (~$1M).

Giles: not worth the money.

4. How to encourage high-risk proposals

Stephen: This instruction can be specifically given during the regular TAC process, but how to encourage this in the DPR process is not clear. One suggestion is to have OT having a box for proposers to identify it as a high-risk/high-reward program, and have some metric (a special TAC/members) that to pay close attention to proposals of this kind. Exactly how to implement it is still in discussion.

Chris: DDT is one option for such kind of proposals. Some proposals of this kind might need a significant time, so large program venue might be a way to do this. JCMT has a solid time for large programs, so don’t think they are missing high-risk programs.

Stephen: IVC suggests the observatory should consider more such kind of proposals.

DDT can only accommodate median/small time require for high-risk proposals, so this won’t work for proposals requesting for a large amount of time.

Action: Ask Rachel how HST (or other observatories) handle this issue?

Response from Rachel: Thanks for the notes, and apologies again for not being able to make it. HST doesn't have a category to flag high risk/high reward programs; that's generally something that gets fleshed out in the discussion of the proposal. There's no metric to keep track of this. We do have different proposal categories, broken up by size (small, medium, large) and type (regular, treasury), and for the categories by size each one is treated a bit differently, and there are separate allocations for each category. Treasury proposals can be of any size, and either observations or archival, but have a higher bar to meet in terms of legacy status (this has an implication for how much $$ a proposer will receive, and an expectation of returning high level science products to the MAST archive). It seems like there could be some ambiguity in how to quantify high risk/high reward if one were to start tracking this.

Recommendation: A small portion of DDT time can be used for strategic proposals as proposed/reviewed by science staff/a focus committee

Stephen: IVC suggests that the observatory should use up all left-over DDT time with high-risk/high-reward projects that have strategic value. Strategic proposals can come from science staff or ASAC members.

Crystal: The difficulty is you don’t know how much would be left in DDT until the end of cycle. An example of strategic proposal: observation of Betelgeuse, with observation script in hand that can be executed in any time.

-- AlWootten - 2020-02-26