[mmaimcal] Agenda, MAC meeting Weds 28 July

[Al Wootten]

Agenda for MAC meeting Weds, 28 July 1999 at 12pm EDT.

Phone: (804)296-7082 (CV SoundStation Premier Conference phone).

Proposed Agenda
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Correlations -- Webber

Chuck Broadwell has posed a science question for the correlator. At the
moment, when you are operating some part of the array in autocorrelation
mode, it appears difficult to provide the increased number of frequency
channels you get in cross-correlation mode. That is, in cross-correlation
every time you cut the bandwidth in half, you also double the number of
frequency channels so that the frequency resolution is improved by a factor
of four. For autocorrelation, the total number of frequency channels in a
given mode would remain fixed, so that resolution would improve only by a
factor of two when the bandwidth is cut in half. This restriction makes it
possible to operate one subarray doing single-dish mapping while the
remainder of the array runs in interferometric mode. Is this restriction
acceptable from the science standpoint?

The MMA ImCal group discussed this on 26 July.  This restriction may require
some observations to be taken in an over-resolved mode, with the data smoothed
in software later.  We could not identify a reason why this would not be
scientifically acceptable.

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Configurations - Helfer, Radford

A meeting was held after the Imaging99 meeting in Tucson, at which US,
European and Japanese interests were represented.  A report is available at
http://www.cv.nrao.edu/~awootten/mmaimcal/confignotes.html

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WVR 

A meeting was held after the Imaging99 meeting in Tucson, at which US,
European and Japanese interests were represented.  A report is available at
http://www.cv.nrao.edu/~awootten/mmaimcal/wvrnotes.html
This week, the Imaging and Calibration group will issue a recommendation to use
WVR at 183 GHz on the ALMA.

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URSI, MOC, Audit - Wootten, Brown

Update on URSI, the audit and consequences, as well as the MOC report. 

URSI  In addition to the 14 August workshop, there
will be a 17 Aug meeting with the European DHs at URSI. If any of you are 
going to the URSI meeting, would you please let Bob know and plan to 
participate in these discussions? 

The May report of the Millimeter Array Oversight Committee is available on
the WWW.
http://www.mma.nrao.edu/meetings/oversight/mmaaoc_report_may99.html

Antenna proposals
are in and are in the process of consideration.  Procurement and
Management subcommittees for consideration of the antenna proposals will
present their preliminary conclusions within a week.

Audit  Geoff Blake attended as a representative of the MAC, for which service
we thank him.  Neal Erickson was an auditor.

 We need to obtain input on the descope
options (Q band, combining 3mm bands into one) which the Audit committee
proposed.   Of course, descope options for the US reference project MMA may
not necessarily apply to ALMA.  However, there is a premium on space in the
dewar for the MMA antennas, and these are possible options for the resolution
of this space crunch.

 It might be possible to get the impossible eleven bands currently
designated for the dewar down through two descoping means: 1) eliminate 7mm
or 2) combine the two 3mm bands into one 70-116 GHz band. A sizable chunk of
science would be lost from option 1), which Carlstrom is writing a report
on. However, some engineers and a contingent of the ESO partners favor this
option. Little would be lost from option 2), however, but there is concern
about a) loss of sensitivity at band extremes, owing to uncertain
performance of the OMT--Wollack will investigate this; b) 1/f noise in the
HFET which would presumably be necessary to cover this band; and c)
broadband first mixer for that HFET which is not currently available. At
the moment the best plan seems to be to ask the receiver group to evaluate
factors a, b and c, as option 2) might be preferable to option 1). BIMA
currently covers the band 70-116 GHz in a single polarization with
narrowband SIS devices.
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ALMA Science Meeting

I will update everyone on the status of this event.
Posters will be available soon.

Current estimate of number of attendees:
32 members of SOC (includes MAC/SAC/JAC members)
 5 members of LOC (not included above)
28 non-MAC speakers (some few have not responded--reminders were sent out 
   earlier in the month)
61 WWW registrants (some overlap with above; only 7 have paid)
Estimate about 120-130 registered attendees.  Auditorium holds 400.
Estimate ~ 50 poster papers.  Posters in reception hall, 57 x 29 feet.
Information on the meeting can be found at:

http://www.mma.nrao.edu/science/science99.html
he meeting will be held at the Carnegie Institution of Washington, 1600 P St. 
NW. Accommodations are being arranged at the Omni Shorham Hotel. A limited
number of rooms will be reserved, so early reservations are advised. 
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Action Items 26July99


       a) A plan for deploying the remainder of the receivers after the initial three.
       A plan exists as part of the US-only MMA reference project; this 
 plan may not apply to ALMA.

       b) Digital FIR filter for the correlator-can the loss of efficiency be decreased to acceptable levels?
       Plan presented at May MAC meeting and approved.

       c) Phase Calibration-necessity for fast switching and implications for hardware; water vapor monitoring- 22 GHz vs 183 GHz lines.
       While little data exists at 183 GHz, the MMA WVR system will be planned
 to operate at 183 GHz.  A review of this was held on 7 June 1999 (see notes
 above).  22 GHz WVR continues at OVRO and IRAM, 183 GHz WVR has commenced
 at Chajnantor with an initial report due at the 14 Aug URSI workshop.  IRAM
 may try 183 GHz WVR at Plateau de Bure.

       d) Total Power Observations-requirements for receiver stability, 1/f noise, necessity for a chopping secondary, etc.
       Butler is working on a model.  This was among the subjects discussed at
 the meeting at the AOC two weeks ago on imaging.  A problem has been the
 development of software for simulations.

       e) Array Configurations-what are the most useful configurations, especially the most compact ones? We need to understand the pros and cons better.
       A meeting was held 9 Jun 1999 in Tucson to address configuration issues.
       http://www.cv.nrao.edu/~awootten/mmaimcal/confignotes.html
Helfer and Radford developed a specific configuration for the US 
 reference project MMA and are now developing this into an ALMA strawperson
 configuration.  The Imaging and Calibration group are working on developing
the criteria for judging configurations.  On 23 July 99, a meeting was held
in Socorro to go over software requirements for simulation.
 In summary, the AIPS++ group (Holdaway primarily, but with input and 
help from Cornwell and Kemball on AIPS++ issues) will deliver a 
simulation package with image evaluation tools and higher level error 
simulations within the time scales of interest for ALMA project.  The 
initial package with basic tools should be ready in 3-4 months (by the 
end of the year), and a more detailed simulator (including some 
scheduler functions) should be available in 6-12 months.  

       f) OTF Mapping, Focal Plane Arrays, etc.-we need to try to understand how often these are likely to be used and their implications for both software
       and hardware.
       OTF mapping will be employed whenever single antenna data is needed for
 a project.  Focal plane arrays are not currently planned for the ALMA.  It
 may be difficult to incorporate an array into the dewar, though individual
 antennas may be equipped with non-array-standard equipment (e.g. a bolometer
 array).

       g) Testing of the Prototype Telescopes-Where, how long, and what criteria for acceptance?
       Emerson has developed a detailed plan, partly in conjunction with the
 Audit.

       h) Someone to fill the role of Mark Holdaway-It seems like the project needs someone doing the type of things Mark was doing for the project. 
       Mark continues to work closely with the project in his capacity within
 the AIPS++ group.

Clear skies,
Al
+--------------------------------------------------------+
| Alwyn  Wootten   (http://www.cv.nrao.edu/~awootten/)	 |
| Project Scientist, The Millimeter Array                |
| Astronomer, National Radio Astronomy Observatory       |        
| 520 Edgemont Road, Charlottesville, VA 22903-2475, USA |
| (804)-296-0329 voice Help us build The Millimeter Array|
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