Calibration Group Phone Telecon Meeting Minutes - 2003-Aug-21 Attending: Butler, Carter, Hills, Guilloteau, Holdaway, Lucas, Mangum, Welch, Wootten, Wright (apologies to anybody I missed) Agenda Minutes: - Al summarized project news. Important Level 1 milestone reached: groundbreaking in Chile. Construction which has started includes the road (down from the site) and the construction camp. Other important news includes the unveiling of the Alcatel prototype antenna at the ATF (this week). Search for the JAO Project Scientist has been reopened. - Al & Bryan talked about cal group personnel changes. Stephane has left the project, which is a real blow to this group. He is now at Bordeaux. He plans to continue his work on calibration until the calibration plan document is complete, along with a couple of memos. Bryan has also left, for EVLA. He will also continue until the cal plan document is done. He formally starts with EVLA on Oct. 1. Stephane pointed out that Aurore Bacmann is also moving to Bordeaux. She will probably continue in collaboration with Stephane on the cal plan document and memos, but will not continue ALMA work after that. All of these changes will require a significant restructuring of the group this fall/winter. Al will start recruiting. - Bryan noted that the updated Project Book Chapter 3 (now called "Calibration of ALMA") has been released. It is not quite complete, in the sense that it is a bit rough around the edges still (especially near the end), but it was considered more important to have it released as a precursor to the cal plan document in its current form rather than attempting to polish what was left. Comments on content are encouraged, but the document itself will probably not be revised significantly (rather, comments should be incorporated into the cal plan document). It should be submitted soon to ALMAEDM and to the almacal maillist. [as an aside, before everybody had phoned in, the following discourse took place: Mel said he thought the "Calibration of ALMA" document was very thorough, but that it faded in the end (after a fantastic start). Bryan pointed out that the polarization especially needs work, Al & Mel agreed. Mel thought that a mention of the offset pointing by using an optical telescope should have been made. Bryan agreed, and pointed out that he, Al, and Jeff had been discussing this a bit. Jack and a student have been working on this at BIMA. It has good potential when skies are clear, for stiff antennas. Bryan pointed out that Jeff has thought alot about this, and has experience on both the 12-m and now with the prototypes. Richard pointed out that some of the worst pointing is in daytime - could the current optical pointing system work then? Jeff answered that it does work - it has an IR filter - and stars to 6th mag can be seen. But there are problems with focus matching on the CCD between optical & IR filters (because of a backreflection on the CCD in the IR - we might need a better CCD if we really wanted to do this properly). All agreed that the technique has promise but needs more testing/study] - Bryan then started the discussion on the outline for the cal plan document. He pointed out that the list of leaders is not finalized - if folks have a problem to get in touch with him. Ditto on list of "helpers." There is still large uncertainty on who will do the polarization section - we *still* lack for such a person in the project (since the departure of Steve Myers). He pointed out that the "Calibration of ALMA" document can be used as a good starting point, but that an important missing element in that document is a good definition of the calibration timescales (this is done in memo 372, and needs to be updated and done properly in the cal plan document). This then should feed into the decision on the size of a Scheduling Block (important for the software guys). Stephane pointed out that there was a serious omission in the current outline - the archiving of calibration quantities. Such an archive could be important in understanding the long term behavior of sources, sky, and instrument. Lucas agreed. Butler also agreed and suggested that we have a separate section for that. Stephane pointed out that it might be better to have a small separate section but to also include in each other section a description of what items should be archived and at what rate. Bryan agreed, and wanted to call this software issues, but Stephane pointed out that it's not really software, but more an operations issue (Robert agreed). Bryan pointed out that there is a serious point to be considered here though - the software group (based on recommendations from the SSR) has been assuming that at least some calibration quantities can be carried across SBs. This has not been clearly defined (*which* quantities, and over what timescales), and the cal plan document should help us to determine this. Also, not every calibration quantity should or will be archived and we need to determine which are, and which are available in real-time to the array M&C system. Robert will probably be the sensible choice as the lead author for this section of the document, given his SSR experience (as subsystem lead for Telescope Calibration). The goal is to have a first draft of the entire document by mid-September (by the time of the next telecon). - Bryan tried to find a good time for the next telecon. This is proving difficult, given that mini-ALMA Week is right about the time which would be right (Sep 17-20). Earlier that week might work, but folks might be on travel. The next week is too late, if it is meant to give us time to revise the cal plan document and still have it done by the end of September. The 15th might work, but Mondays are hell to try to get a time for a telecon. Bryan will send out an email querying folks for what times are available. - Bryan pointed out that a face-to-face meeting in the fall will be tough, given personnel changes. All agreed. A meeting is still needed, but perhaps in the spring. Depends on filling the positions. - Stephane pointed out that there is an urgent need for a change request at the project level for the receiver calibration device. This would be to evaluate the cost (and other) impact of the new device designed by Matt. This requires some transfer of "value" from NA to EU. This is pretty urgent, as there is currently no funding for the current design in the project. Richard pointed out that this came up at the Groningen FE meeting, and that the FE IPT leads were of the opinion that it hadn't been demonstrated that the simpler designs would not meet the requirements, so they issued an edict to cease and desist all work on calibration devices. Matt echoed that this was the current situation. Al will get together with Charles Cunningham to try to get this sorted out. Bryan pointed out that Stephane's new memo (461) provides us with some ammo for this argument. - Mark expressed some concern about the state of the project. Richard pointed out that at least with respect to calibration, we will be in some difficulty in the short term, but we are in a situation where we know basically what needs to be done, and that the plan will certainly evolve (even after the construction is complete). Al pointed out that we just have to carry on as best we can with the resources we have and get the job done. - Bryan pointed out that we should add in the cal plan document either a separate section, or an item within each section, which describes the tests or studies which are still needed to be done. Mel asked how much time was really available on the ATF for this kind of work. Al thought that after January we would have some significant chunk of time. But one of the antennas goes away in September. Bryan pointed out that the ATF interferometer has basically gone away. Richard expressed dismay (again) at this situation and asked what could be done. All agreed that interferometric tests were very important for calibration. Richard pointed out specifically (again) their utility for WVR testing. Even on a short baseline, where phase fluctuations might not be too large. There was some discussion of whether the Japanese antenna could be used for this. Al pointed out the difficulty, given completely different control systems. Richard pointed out that this didn't stop the CSO-JCMT interferometer - basically you just have to have a way to point at the same source, control the frequencies, and get the IF out of the two antennas to a correlator. dutifully scribed by bjb with input from haw on 2003-Aug-21.