ALMA Science Advisory Committee
 
 

Teleconference, 12 April 2001
 
 

Draft Minutes

Participants: A. Benz, G. Blake, L. Bronfman, Y. Chikada, P. Cox, R. Crutcher, D. Emerson, N. Evans, Y. Fukui, B. Glendenning, S. Guilloteau, M. Gurwell, T. Hasagawa, M. Ishiguro, R. Kawabe, R. Lucas, H. Matsuo, N. Nakai, M. Rafal, G. Raffi, J. Richer, S. Sakamoto, K. Tatematsu, E. van Dishoeck, M. Walmsley, W. Welch, C. Wilson, A. Wootten, S. Yamamoto, M. Yun
 
 
 
 

The proposed agenda was adopted.

The minutes of the March meeting were adopted as slightly revised and will be posted on the WWW.
 
 

1. ACC Meeting in Tokyo; Formation of Expanded ACC

S. Guilloteau summarized the recently concluded meeting of the ACC and the ALG in Tokyo. The ASAC was delighted to hear that a  resolution was signed on the joint planning of a three-way partnership, even though the exact wording proved difficult.  An Expanded ACC (EACC) was formed with Japan fully represented. Discussion centered on establishing the boundary conditions for the enhanced ALMA (Atacama Large Millimeter/Submillimeter Array); there was concern that additional partners not bring overhead only to the project but real scientific capability, a mandate to the Enhanced AEC. This includes antennas, where the cheapest possible solution must be found including construction and operation. The funding level was also broached. Dr. Eisenstein mentioned a U. S. target construction budget of $200M plus $20M from Canada in 2000 U. S. dollars. Assuming a 33% share for North American, European and Japanese partners this suggests a budget of $660M in 2000 dollars, not including Phase 1 or interim funding. An upper boundary for funding was defined at the original $552.4 construction cost times 1.5 for the new partner, less 10%, or $746M in 2000 dollars. The EAEC was assigned to define the three way project at the minimum level, with attention to what additional science might be achieved at the higher level. This will be accomplished by a meeting of the EAEC + IPT leaders in Paris 10-11 May, and subsequent discussion, leading to the next meeting of the ACC in Munich 11-12 June. Ewine suggested that the ASAC needs to strengthen the case for the additional three receiver bands and the enhanced correlator, though there are no priorities placed on these items yet. By May 8 a one page summary case plus figures for bands 1, 4 and 8 will be presented to the ASAC. Working on these will be:

Band 8: Yamamoto, Walmsley and Tatematsu. Band 1: Richer, Myers and Blake. Band 4: Cox and Yun. Project scientists will also participate. The Japanese are preparing a memo on enhanced science with the correlator; a similar description will be produced for the future correlator. The possible savings by relaxing specifications on DSB/2SB/SSB requirements will be studied by project scientists, with issues highlighted and presented by 8 May. Important considerations will be the mix of projects between continuum and spectral line, single antenna and interferometer observations, and under differing weather conditions. Furthermore, the Operations addendum to the European Construction Proposal has been circulated and will be discussed at a future teleconference.

There were also discussions on ALMA in Chile; a letter of interest from Dr. Ricardo Lagos, President of the Republic of Chile, to Dr. Catherine Cesarsky, President of the ACC was presented. In translation, this letter reads in part "Through this letter, I would like to express the interest of the Government of Chile in initiating negotiations leading to the installation and operation of this important instrument within our country."

The report of the ASAC was given to the ACC by Jack Welch, and very well received.

2. Face to face meeting

The next face-to-face ASAC meeting will take place in Chile in September. Exams in Japan and SIRTF activities suggest that the meeting occur in the second week, so this would in turn suggest a plan as follows: day –1 (9 September): San Pedro; day 0 (10 September): Chajnantor site; days 1,2 (11, 12 September): ASAC meeting in Santiago; day 3 (13 September): ALMA science day. A day –2 (8 September) may be added to allow more time in San Pedro for acclimatization and rest.

3. Data Handling

The committee gratefully received the report from Glendenning and Raffi, which was introduced by Glendenning. ALMA has not funded an ALMA-specific post processing package, beyond those which retrieve raw data into a usable format and apply first calibrations. The output will be in a package-neutral FITS format. The Science and Software Requirements group is preparing a list of requirements for this system. A European proposal for an AIPS++ demonstration project at IRAM has been well-received at NRAO.

NRAO is committed to ensuring that AIPS++ can handle ALMA data, and other institutes are of course free to make similar commitments.

Benz noted some concern about AIPS++ independence of ALMA and its users. Evans inquired whether AIPS++ has accepted responsibility for ALMA data, to which Glendenning reported that it was an NRAO commitment. Crutcher, a member of the AIPS++ Executive Committee, reported that management had a strong enthusiasm for this charge and could comment about this at its next meeting in about one month. Ewine queried the timescale, personnel and evaluation criteria for the IRAM tests, to which the response was 9-12 months, NRAO personnel, and to be determined. Crutcher further noted that AIPS++ does not yet support the full spectral flexibility of the BIMA correlator, and it is reported that only continuum VLA data has gone end to end through AIPS++. An Illinois workshop where users can bring their own VLA and BIMA data is imminent and a report will be forthcoming.  Gurwell, Benz and Tatematsu will craft an official ASAC comment.

On pipeline, data rate and archive issues, Hasegawa noted that a Japanese group is assessing accommodating the data rate increase which will occur with an upgraded correlator.  Their report will be available later in the month.

The Scott and Myers document included within the Glendenning and Raffi report details current data rate estimates, which will allow as in this Table:
 

Tradeoffs between integration time, channels, and phase correction for visibilities.

Both and Single refer to the atmospheric corrected and/or uncorrected data selection.

John Richer announced the calibration meeting in June, with a focus on everyday calibration by ALMA.

5. Next ASAC teleconference

The next ASAC teleconference will take place on Thursday 17 May at 14:15 UT.