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)



 - 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.