[asac] [almanews] ALMA News - 2000-Nov-03

[Al Wootten]

The following news item went out this morning but I think did not propagate
to the ASAC.  I pass it on for your information.  Our next phone meeting will
be one week from Monday, at 10:15 EST.  The minutes for the last teleconference
may be found at:
http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacminutesoct00.html

Please forward any agenda items which you feel should be addressed to
Jack, Ewine and/or me.

We have combined two of our email exploder lists (amemoannounce and
almanews) to be able to reach the maximum number of people with ALMA
Project information.  The "new" almanews exploder will periodically send
out abstracts on the various reports and memos, with links to the full
versions, that are distributed throughout the Project.

If you have questions about the ALMA Project or concerning the email
exploder, please send email to cwhite at nrao.edu, ALMA Project Secretary.

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Report of the ALMA Science Advisory Committee

The report of the most recent meeting of the ALMA Science Advisory
Committee (ASAC) was accepted by the ALMA Coordinating Committee at
their meeting of October 13.  That report includes a summary of the
following issues discussed by the ASAC:

    1.  The Enhanced ALMA (with Japanese participation)
    2.  Correlator Issues
    3.  Array Calibration
    4.  Water Vapor Radiometry
    5.  Receivers and Frequency Bands
    6.  Polarization
    7.  Array Configuration
    8.  Test Interferometer
    9.  ALMA Site Characteristics

The major conclusions and recommendations resulting from the committee's
discussion are:

- The ASAC re-iterates its strong support for the participation of Japan
in the ALMA project as a full partner. For the Enhanced ALMA resulting
from such a partnership, the possibility of an Atacama Compact Array of
10-16 antennas of size 6-8 meters and adding complete frequency coverage
have the highest priority because they both enable new science to be
done. Other enhancement options are additional array antennas and an
enhanced correlator. With regard to the Atacama Compact Array, we
recommend studies of its imaging performance to determine optimum values
for the size and number of its antenna elements.

- The project team working on the future correlator solicited ASAC input
on a variety of items. Our recommendations are listed in section 3.2.

- Regarding calibration, the ASAC concludes that there should be no cold
loads in the dewar. Current ideas, particularly the semi-transparent
vane and the use of coherent signals should be developed further. A
calibration accuracy of 1% is adequate.

- The ASAC very strongly encourages further work on developing a phase
correction scheme using water-vapor radiometry at 183 GHz and 20
microns. Various efforts are under way and should be pursued
concurrently.

- The ASAC confirms that the highest priority receiver bands to be
initially installed are bands 3, 6, 7, and 9. Second priority bands are
1, 4, 8, and 10, while third priority is assigned to bands 2 and 5. The
ASAC requests to be involved in all further discussions on
prioritization of receiver bands. We again request a presentation at the
next ASAC meeting of a detailed plan for the mass production,
integration and testing of the ALMA Phase II receivers.

- A number of detailed recommendations concerning polarization are given
in section 7.4.

- A thorough comparison of the Pampa la Bola and Chajnantor sites should
be made using as much contemporaneous data as possible.

For access to the full committee report see:  

    http://www.alma.nrao.edu/committees/ASAC/
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