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ALMA Science Advisory Committee

Teleconference, 10 July 2000

Draft Minutes

Participants: Bronfman, Brown, Cox, Crutcher, Emerson, Guilloteau, Ishiguru,
Menten, Shaver, van Dishoeck, Welch, Wild, Wilson, Wootten, Yun


The draft agenda was accepted as proposed.


1. Japanese Participation

R. Brown summarized the recent ALG meeting. Japan is presently carrying
out a costing exercise, in preparation for a review on 28 July, and
anticipates a decision on funding about a year from now. The ACC had
recently stressed that the US-Europe project must not be considered
incomplete, that Japan will be enhancing the scientific capabilities of
an existing project. Thus, the Japanese proposals:
a) to preserve the sensitivity per partner - this implies 78 x 12m
antennas
b) to restore all receiver bands to the project (actually eight science
bands and one WVR band, omitting band 2 (as band 3 should go to 86 GHz)
and band 5 (because low priority))
c) to provide short-spacing capabilities with a small-antenna array
d) to become involved in the future correlator development.

There was discussion about the small-antenna array (ACA). Operation
would be much harder if it is on a separate higher site - the ALG
prefers a location close to ALMA. K. Menten commented that there is as
yet no official ASAC report on this. Various groups are working on the
ACA issues: Guilloteau, Viallefond, Yun, Morita, Welch, Holdaway. S.
Guilloteau will put a document on the web soon, and have a full report
in October. This will be an important issue at the Berkeley ASAC.

The idea of having 8 bands instead of 10 was questioned, in terms of
spectral line coverage and redshift coverage. This will also be
discussed at the Berkelely meeting.


2. ALMA Receiver Development

W. Wild explained the current limitation of only 3 receivers on at any
one time. The limiting factor is heat load at the 4K stage. Other
receivers would be available within 15 minutes (maximum) - this time
could be much less, a few minutes, but 15 minutes was adopted for the
present as a conservative upper limit. Various groups are working on
aspects of this issue. 

W. Wild also stressed the need to decide soon on the calibration scheme,
as it drives the optics design. S. Guilloteau commented that, on the
other side, it was important to know (first) what was possible
technically. K. Menten asked the Project Scientists and Receiver Group
to iterate on this, and the issue will be discussed at Berkeley. On the
question of the calibration requirement, A. Wootten and J. Welch said
that the goal is 1% absolute calibration above the atmosphere. W. Wild
replied that the Receiver Group needs a clear number for the receiver
calibration alone. J. Welch and S. Guilloteau said that work is
presently being done on calibration schemes at Berkeley and IRAM, and
results will be presented at the Berkeley ASAC.


3. Agenda for Berkeley ASAC

A number of topics were mentioned: the ACA, receiver issues, correlator
plans, configuration issues. C. Wilson mentioned other items from the
list of "future issues" from the Leiden meeting: Phase 2, LO systems,
software, spectrum management, site, outreach.


4. AOB

A. Wootten mentioned the good result from the Istanbul meeting on
protecting mm wavelengths. He also mentioned that A. Benz is organizing
a meeting at the Manchester IAU GA on solar and pulsar science. K.
Menten said that he and the Project Scientists will send around an
e-mail on plans for the Test Interferometer.
  


5. Next Teleconference

The next telecon is scheduled for Monday 7th August at 14:15 UT.