[mmaimcal] Minutes 9 Nov

[Al Wootten]

MMA Imaging and Calibration Group

Minutes for meeting Mon, 9 November 1998 at 11am ET.

Date: Monday, 9 November, 1998

Time: 11:00 am EST (9:00 am Socorro, 9:00 am Tucson)

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

Past minutes, etc on MMA Imaging and Calibration Division Page

Minutes

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In attendance: CV: Wootten; AOC: Glendenning, Rupen, Butler, Yun TUC:
Mangum, Helfer, Radford.

Report from antenna meeting in California -- Butler

On 4 Nov, Butler, Brown, Woody, Churchwell, Carlstron, Welch and Blitz met
at Berkeley to discuss antenna diameters. The deliberations concentrated on
science drivers in the morning, and technical issues in the afternoon.

Conclusions from the science discussion were:

*A class of interesting single-pointing observations exists--distant
galaxies, some stars, Kuiper Belt Objects and asteroids, and similar small
objects. For these observations, nD2 should be optimized.
*In spite of the above, most observations with the LAMA will be
mosaiced--notably, star formation regions will need to be mosaiced, to
understand how the protostellar envelope ties in with the inner region.
Interpretation of a single pointed image made of the central star formation
region cannot proceed on sound footing without knowledge of the surrounding
region. For these observations, nD should be optimized.
*Any diameter can provide these mosaiced images if the antennas meet
specifications, including total power capability.
*Sensitivity increases with diameter.
*A minimum sensitivity exists with which the array will be capable of
addressing high z problems, as well as gaps caused by forming planets in
protoplanetary disks. This drives nD2 upward.
*Similar quantitative arguments for characterizing a minimum value for nD
for the LAMA need to be made, and are currently being formulated.

On the technical side, one can "push" in one of three areas during
development--antennas, electronics, or correlator. It was thought (given
later argument) that the correlator wouldn't necessarily need to be
agressively pushed. If it is decided to push antenna design, there is
necessarily a large risk involved. The antenna is a major expenditure, and
possibilities for upgrades to the antennas are limited. The antennas should
therefore be built with the most advanced technology which poses a minimum
of risk. The electronics offer an opportunity for major technological
advances. However, if these advances are not realized, we will have missed
the opportunity to have pushed on antenna design. An example where antenna
design was pushed is the GBT. An example where electronics design is being
pushed is the 1 Hectare Telescope.

The cost equation was revisited, including scaling with D, receiver number,
maintenance and operations (scales as ~0.5n) and risk analysis. A study by
Napier indicated 30% contingency for 10m antennas and 35% for 12m was
prudent. Then antennas plus receivers for an LMA which total the $200M
expected budget (for antenna + receiver costs only) include:

*93 x   8m   =>   nD ~ 744;   nD2 ~ 5952;   A ~ 4675 m2
*67 x 10m   =>   nD ~ 670;   nD2 ~ 6700;   A ~ 5260 m2
*48 x 12m   =>   nD ~ 576;   nD2 ~ 6912;   A ~ 5430 m2
*31 x 15m   =>   nD ~ 465;   nD2 ~ 6975;   A ~ 5480 m2

These numbers should not be taken as real estimates of the number of
antennas in the final LAMA, but rather as illustrative of the tradeoffs
between number of antennas, and the two products nD and nD2. This analysis
will be done more carefully by Brown. It seems apparent from the above table
that in order to optimize both nD and nD2, either the 10m or 12m diameter is
preferred. 8m pays a large penalty in nD2. 15m pays a large penalty in nD.
There is only about a 15% difference in nD, and about a 3% difference in nD2
between the 10m and 12m designs. However, the risk is much greater with the
12m diameter. The NRAO 10m design scaled to 12m would be unable to meet the
current specifications. The OVRO 10m design (with its many clever features)
scaled to 12m is just barely able to meet the specifications for pointing
and surface accuracy. The 10m (or 8m) design could meet the specifications.
However, the total number of antennas (and hence receiving systems,
cryogenics systems, etc...) is about 50% greater than for the 12m antenna.
This material will be written up by the members present, and submitted to
the MAC for consideration.

Butler visited the lab at Berkeley and reported that the three load cal
system is working well in the lab, whizzing along with a 50ms integration at
each load, with little apparent vibration. It is hoped that this will soon
be mounted on an antenna.

Butler reported that OVRO plans to use 3 WVR channels this winter, and that
the BIMA/U. Md. backend might arrive at the site sometime in January.
Radiometer feedback problems in the VLA WVR have been repaired and tests on
antennas should begin within several weeks.

MAC meeting -- Wootten

Wootten will report on the Frequency White Paper, and fast switching. Butler
will report on 22 GHz water vapor radiometer plans and operations. Yun will
report on 183 GHz water vapor radiometer plans and operations. Mangum will
report on calibration issues. Wootten will also lead a discussion of the
Scientific Meeting planned for next year.

Project Book -- Wootten

Wootten is updating Chapters 3 and 13; Helfer is working on Chapter 15, and
Brown is working on Chapter 2. Drafts are due 11/16/98 with final copy by
11/30/98.

Standard Talk -- Wootten

Wootten and Smiley are developing a standard presentation based upon a
suggestion of Brown's. This is developing on the MMA Imaging and Calibration
Division Page for the moment. Note that copies of most of these viewgraphs
were distributed to Weatherall in Socorro, Webb in Tucson, and Smiley has
sets in Charlottesville. Uson also has Spanish language versions of some of
these (Dated Fall '97, so old). A Spanish version of 
the description book is also available (ask C. White for the August 1998 
version).

Notes from Division Heads Meeting:

The WBS is complete, and in "published" format.  The complete 
Gantt chart (a listing of all
tasks with an attached graphical timeline) is available at
http://www.cv.nrao.edu/~rsimon/mmagantt.pdf.  An index is included, so
you can easily find your favorite section.

The WBS Dictionary is also now available, also with an index page, at
http://www.cv.nrao.edu/~rsimon/wbsdict.pdf.

Finally, the list of milestones is on line at
http://www.cv.nrao.edu/~rsimon/mmamlstn.pdf.  

Japanese Meeting
----------------
<p>
The Japanese are trying to gain more support by staging this high
profile meeting in government plaza.  They are hoping to get more
input from government bureaucrats.  There is much competition for the
monies from the high-energy physics and gravity wave sciences.
<p>
Europe Meeting
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<p>
ESO and the UK initialed the MOU on Friday, 06Nov.  The initialization
of the MOU means that the European Coordination Committee (ECC) has
been set up.  The ECC will consist of mainly bureaucrats not
necessarily astronomical people.  This will allow them to assign a
Project Manager and Project Scientist within 31 days.  The Dutch,
Germans, and French also initialed, which means they are giving money
outside their usual ESO contribution.  This will enable them to have a
stronger voice.  The combined funding is $15 M.  The
Dutch contributed to the receiver development, the Germans to antenna
development, and the French have not decided.
<p>
-------- Action Items 9 Nov98

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URSI Meeting (Radford) Schedule

-------- Travel

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T. Helfer: 26Nov-09Dec (Tenerife)

A. Wootten: 18-19 Nov (Green Bank) 20-22 Nov (Chi) 12-17 Dec (AOC)

J. Mangum: 20-22 Nov (Chi)

M. Yun: 20-22 Nov (Chi)

B. Butler: 3-5 Nov (UCB) 20-22 Nov (Chi)

S. Radford: 20-22 Nov (Chi)