Calibration Group Phone Telecon Meeting Minutes - 2003-Oct-09 Attending: Butler, Carter, DiFrancesco, Hills, Holdaway, Mangum, Pintado, Radford, Sterling, Welch, Wright, Wootten (apologies to anybody I missed) Agenda Minutes: - Project news. Al summarized results from the Correlator CDR. The major change is to replace the polyphase filters with completely tunable ones, ameliorating the aliasing problem at the subband edges and allowing for more tuning flexibility. Overall the correlator seems to be in very good shape. The AMAC will meet next week in Holland. Al does not have to go, as Ewine will make the Science IPT presentation. The ALMA Board will meet in Santiago on November 3-4. Ground breaking will occur on November 6. The road from the site to the OSF (and thence to the highway) is nearly complete. - Al then started the discussion on the amplitude calibration widget. ALMA week (Victoria) miscommunication resulted in the S/T vane tests on the 30-m being suspended. A new contract to continue this testing (between ESO and IRAM) is being finalized - hopefully it will be signed by Monday October 13 (according to Matt). The testing will include finishing up tests on the current S/T vane device (notably doing real astronomy on the sky). It will then progress to a new wire grid system with multiple loads, and finally, the full-up system described in memo 461 will be designed and tested. Different couplers (S/T vane, wire grid, dielectric film beamsplitter) will also be tested on the final device. Eventually, the complete ALMA system, with real front ends, dewar, etc..., will be tested at the OSF in late '05/early '06. This has necessitated several WBS changes (with a formal CRE request from Al). The testing plan and formal CRE are linked from the agenda. Between Matt and Jesus-Martin, the telescope time will get scheduled somehow. Bryan pointed out that we still might get some relief on the amplitude calibration requirement from the ASAC (see notes from 2003-Sep-15 telecon on this). We will not know until the ASAC report comes out after the ALMA Board meeting (Nov. 3-4). - Bryan then started the discussion on the calibration plan document. He expressed some dismay at the lack of response to the October 1 deadline for folks to have drafts of their contributions in. Only BB and Jack had contributed anything substantial. He suggested that all leaders should attempt to have at least crude drafts in by October 15. If we can at least have a unified draft by the end of the month, this would be good progress. Al pointed out that this document should be compatible with the Science Requirements document, but did not necessarily need to agree with the System Design document that Larry D'Addario is working on currently. - Mark then discussed the new memo by he and Larry. It considers sensitivity loss due to opacity as well as decorrelation. It does not include sensitive imaging simulations. Richard pointed out that these effects should be baseline dependent, i.e., the electronic noise will show up on short baselines more often than Larry and Mark have assumed (95% of the time things are limited by atmosphere). Mark pointed out that the fast switching effective baseline is 100m. Mark and Richard agreed that the treatment of the effects as a function of baseline length should be explicit. Further discussion on this topic is warranted, and could perhaps be a topic in a Science IPT telecon. - Richard then introduced Alison Sterling, who is a new member of the Cambridge group working on WVR issues. Her background is a combination of meterology and astronomy - well-suited to the task at hand. She was welcomed by all. - Al pointed out that the job announcement for Bryan's ALMA position had been released internally at NRAO, and had received two responses. He will be doing interviews in the near future. This new person could conceivably start by the end of the year. If no qualified internal candidate is found, the announcement is made to the outside world, and the timescale will be longer. - We discussed briefly our next telecon. Bryan pointed out that it's probably not appropriate for him to run these telecons any more, given that he's no longer formally employed by ALMA. Al agreed, and somebody else will take over this responsibility. dutifully scribed by bjb with input from haw on 2003-Oct-13.