scipt 15 apr 2003 Mangum, Hasegawa, Cernicharo, Roueff, van Dishoeck, Saito, Wootten, Tatematsu, Conway, Testi, Butler, Wilson, Guilloteau, Lucas, Pety, Ann, Richer EvD called the meeting to order. SG: ASAC meeting was the big item. Wilson: No overall items to mention. The six charges are pretty relevant to this group. We got quite a bit done given lack of advance notice on the charges; information was lacking on some items. On this agenda, Front End specs are not covered, nor are the inhomogeneous array. Inhomogeneous array--contributions from Wootten, ANATAC and SG. ASAC uncomfortable with multi-antenna designs. Polzn and mosaic science most likely to be affected. Also an impact on software efforts. Other costs also less obvious, and take away from resources which could be expended on science. Front End--FE Specs document received. Frequency ranges good as specified. Sensitivity looks good, meets earlier specs set by ASAC. Reiterate that Bands 7 and below should be 2SB. Gain stability specified in document and should be targeted. Continuum OTF imaging affected by this. At levels of 3 e-3 then calibration might be affected. Missing reqmnt on phase jumps on changing bands which was in an earlier version of the document is now gone. EvD: Frequency range on Band 4 might be extended to higher frequencies, we noted. Gain stability needs some simulations. CW: Report to be sent to Board by early May, to become public after presentation to the Board. Fast data rate: See the document from Richer which is a draft for discussion. JR: This is basically a response to Steve Scott's rec on increasing the data rate which ALMA will handle. The Sci IPT was asked to comment on how reasonable this was. The result is that the rate will limit science but not in an extremely severe way except for OTF interferometric imaging. The tradeoff point suggested is quite reasonable. Compression of uv data at some point in the system, perhaps a few months after collection, may help with archive size, relieving this consideration on datarate. BB: On point 8, you might need more bit values for each complex visibility than 1 x 16 bit if you wanted to also store a weight for each visibility. At the VLA for high dynamic range, this is required. SG: For each channel as well as each visibility? BB: Perhaps a weight per bandpass (an-based) and for visibility. Mel Wright--surely not needed for every time stamp and channel. BB: I would argue that you do for high dynamic range case. So average data rate may depend upon the kind of imaging targeted. SG: One weight per baseline per visibility plus tsys per antenna might be enough. EvD: Please send comments within the next week to PS and to John. We may need to formulate the effect on the archive somewhat more strongly than in point 11. JR: Here this interacts with the ALMA operational model. EvD: Let's make the 28th the deadline. EvD: Operations and design reference mission working group. EvD supposed to propose a name for extragalactic work. SG: We need to get the group fully composed. I will take the action on this; I will send a list of questions and suggestions on how to compose this mission, and iterate with EvD. EvD: Other action items have been done. Let's move on to milestones. Wilson: ASAC comments on calibration were written by John. Presentations from SG and from BB, including tests done on dual load and semitrans vane. These tests suggested that neither would work to level hoped for. We agreed to support a new idea, a polarization grid before a load set. The absolute calibration specification was endorsed pending tests of this new device. Polzn calibration suffers from a manpower shortage; the new vane may help with polzn calibration. WVR should be tested at ATF in interferometry mode. EvD: Most important message is the calibration accuracy goal. BB will you take us through this list please? BB: ATM code sent to me and will be password protected and placed to be available to ALMA workers. Upper level routines are source code, not lower level ones. Draft specs for cal devices met by Hills and Richer email of yesterday. Comments sought. Also we need to add some more mundane weather station items. JR: We will iterate after comment. We need specs also, not sure which milestone that is. Bandpass cal plan, pretty complete with draft presentation--SG says he needs a real draft to be sent in. Aurore is working on this real draft, perhaps ready within weeks. Draft of phase cal plan being worked on by Al. Draft of amp cal plan perhaps until end of May. This needs some new work. Is this SG? SG: end of May should be OK. BB: Review of SSR plan will probably not be done by Myers; can Lucas do this? RL I may be able to do some work on this in May, but someone else should do this. JR may help with this over next weeks. Perhaps new software hire, but someone with awareness would be best. Antenna location determination plan--delay until 31 May? JC is working on configuration. We need to know what to put into this above what Mel wrote. This is a draft, really needed for the end of September though formally leads into June milestone. Draft of delay cal plan--SG says this is part of bandpass so this can be collapsed into that for the end of April. Antenna global pointing model complete, with Mangum memo. Reference pointing model complete with Lucas, Guilloteau Bachiller memo Operations--SG synchronizing with RSramek on this, start next week. Technical aspects of WVR essentially done but not distributed. We need to bring this up to date now that construction is under way. Final plan at ESO for approval. JR: Is there a milestone on the use of the WVR at the VLA site. AW: This should be vetted at ALMA Week. EvD: Can you say something about ALMA Week? JGM: There is a milestone for Q2 Sept 2003 for this. JR will look at this D.2. SG: MT wants to review WVR activities at ALMA Week. GHT and SG are drafting an agenda for that. Please send any specific items before the end of this week. BB: WVR team will be invited to ALMA Week. This is occurring right now. JR: What are Massimo's goals? SG: Items on draft agenda now are into, description of the WVR in the system, programmatics, schedule and mielstone including ATF testing, syseng and status report. Then exec summary and list of actions. BB: We should discuss anomolous refraction SG That is a subtopic on function of WVRs. EvD: Is there a science presentation accompanying this, on modeling or is it part of overall strategy discussion? SG: Yes, it is in the latter as a flowdown. BB: Cal meeting is Thrusday afternoon, WVR on Friday pm. ATF discussionis on Wednesday. EvD: Will decisions be made on the basis of these discussions? SG: We won't have a complete discussion at that time. BB: Drafts need to be assembled by late May. EvD: Interviews held last week on new EU IPT lead, replacement expected by ALMA Week. BB: Next cal telecon end of this month or early May. Configurations: Long baseline designs looking good, good transition from inner array. Some suggestions. Was it possible to move antennas further northeast to increase baselines or to quickly look at multiconfiguration data optimization. How much resolution lost by suppressing sidelobes. BB: Talked to them last night, good success at looking at sites though some are on the far side of the pipeline and hard to get to. JC plan 'E' is submitted and has draft outward move sequence. Still working on inner reconfiguration, difficult owing to shadowing as one does this. SSR: Software, first ASAC response. Focus on evaluating Phase I, II and III aips++ IRAM tests. aips++ needs to have performance within factor of 2 of other packages but it is still a factor of four or so out. Phase I seems to have ended finally with good results. Phase II tests somewhat diappointing, though it ended on time many testers did not finish so that images could be compared. Phase III should be pursued. Pipeline is a critical system. Plan to meet missing ALMA specs needed in light of manpower needed to re-engineer aips++ to meet ALMA specs. Site-- No one is present. BB, AO and SR are working on document to describe radiosonde data and draft exists. Imaging--Questions not responded to yet on sizes of ALMA images, etc. JP: TH: Working on designing ACA system with trial configs, calibration schemes, and schedule. To establish a good configuration we need a design reference mission also of programs needing the ACA. We'd like to share these design concepts. We plan to finish report on concepts of ACA as soon as possible, perhaps as soon as the end of this month. MW: Draft memo on summary of BIMA proposals. Look at the memo, I think it is pretty objective with someone else going over the cover sheets. A quarter of the proposals were mosaic, over 90% spectral line rather than continuum. Integration times even out because of need to sample uv plane. It would be useful to know these results from a submm set of proposals. EvD will do this for JCMT and AW on CSO but SG worries that this will not apply well to ALMA. Next meeting 6 May.