ALMA Board response to the ASAC Report of January 2006 meeting

The Board thanks the ALMA Scientific Advisory Committee for the report 
with its recommendations arising from their deliberations during their 
January 28-29 meeting at the University of Maryland. It is grateful to 
the ASAC Chair, Dr Christine Wilson for her clear, succinct, and directed 
report and for her effective participation in the discussions that followed.

As part of the process of improving its effectiveness the Board requested 
that formal reports such as those from ASAC be transmitted to the Board 
accompanied by a JAO response stating clearly their advice regarding each 
recommendation. The process is meant to ensure that the Board has thoughtful, 
complete information in advance of the meeting at which the ASAC report is 
considered to inform its decisions. The Board is grateful that Interim 
Project Scientist Tom Wilson, with the Director\u2019s concurrence, 
provided the first such report during the Kyoto meeting, and looks forward 
to receiving more detailed JAO responses well in advance of future Board 
meetings.

The summary of the Board\u2019s response to ASAC\u2019s report is detailed 
below, taking account of the comments in response by the JAO.

Charge 1: Review progress in the science software development for ALMA (e.g. 
plans for the observing tools, pipeline system and archive) and how they 
will meet the top level user requirements.

The Board notes that the ASAC strongly supports the decision to make use 
of the ESO experience with data base software, infrastructure and bulk 
data handling. However, the Board notes with concern ASAC\u2019s observation 
that \u201cthe ALMA science archive, which will be the main interface to the 
archive for an outside user, is still in a pre-development phase with the 
requirements and design documents still in draft form.\u201d Because of the 
importance of the ALMA archive to users, the Board requests that the JAO 
report back for the June, 2006 Board meeting on the steps being implemented 
to address ASAC\u2019s concerns, including finalization of the requirements 
and design documents.

The Board finds ASAC\u2019s comments on the progress of the off-line software 
very helpful. The Board endorses ASAC\u2019s Recommendation 5 \u201cthat the 
commissioning team be fully committed to using the ALMA science software 
during commission.\u201d It fully agrees with the importance of testing the 
new CASA package, to be released in 2007, against other systems. The Board 
is grateful for the in-kind contributions by ASAC members and other scientists 
to SSR activities, including CASA testing. It also sympathizes with the JAO 
response that the software testing will be done by the computing support 
group under the operations budget, but notes that it is imperative that 
independent tests be conducted in a timely manner within the community. 
The Board suggests that the burgeoning ARCs and their scientific staff 
could be another important, funded group to participate in this task 
(Recommendation 6). As the ASAC notes, it is imperative that the CASA 
software be adopted by the community and that the project must avoid fall-back 
use of earlier software by making the off-line package user-friendly 
(Recommendation 4). At an appropriate time, the Board will ask ASAC to assess 
further progress in this area.

Finally, the Board will press the project to ensure that the pipeline 
development is timely and that this facility is available for early ALMA 
observations (Recommendation 6).

Charge 2: Review the plans and progress towards the scientific integration 
of the ACA into the baseline ALMA project, e.g. software and calibration issues.

The Board was pleased to learn of the substantial progress by the ALMA-J 
team on detailed planning of calibration and operations concepts, and 
appreciates ASAC\u2019s thoughtful formulation of new definitions to 
clarify calibration accuracy requirements, which merit adoption by ALMA.
However, the Board is concerned by the ASAC observation that \u201cthe 
current ACA expectation for \u201cabsolute flux calibration\u201d is 
5%...with a 5% calibration uncertainty between the two data sets (i.e., 
ACA, 12m arrays), such images would be effectively limited to an image 
fidelity of 20:1\u2026cross-calibration will require a complex and carefully 
coordinated sequence of observations to be executed by the two arrays.\u201d 
The Board strongly opposes the proliferation of observing modes and agrees 
(a view also shared by the JAO) that an analysis of ALMA + ACA calibration 
issues, including the requirements on the ALMA-ACA cross calibration 
accuracy, should be conducted by the science IPT without delay 
(Recommendation 7) . It follows that Recommendation 9 concerning a 
detailed study of the scheduling impact of all modes offered by the 
enhanced ALMA should be restricted initially to modes of highest priority 
once they become clear. Furthermore, the Board will ask the ASAC, in a  
further charge, to look into calibration plans in general.

The Board notes ASAC\u2019s view that \u201cthe priority of the ACA must be 
to provide short spacing information to be combined with data from the 12m 
array,\u201d and concurs that the possibility of operation in the combined 
mode should not be designed out of the baseline.

Additionally, the Board shares ASAC\u2019s worries about the observing 
technique of chopping during on-the-fly scanning of the total power antennas 
and its effect on data quality (smoothing the TP data). This technique and 
its usefulness should be studied by the science IPT without delay 
(Recommendation 8). Finally, the Board concurs with ASAC\u2019s 
Recommendation 10 that the DRSP be updated with new projects for Bands 4,8, 
and 10, as well as more detailed information relating to the ACA. It 
encourages the Science IPT to do this no later than the end of 2006.

Charge 3: Review the existing analysis of the polarization and mosaicing 
performance of the hybrid ALMA array and consider the priority and timescale 
for further analysis by the science IPT.

The Board is grateful for the ASAC advice on these difficult but important 
problems and concurs with Recommendation 1 that the project should, with 
some urgency, consider the final optimization of the two 12m antenna designs 
with respect to the shape of the feed legs and the possibility to tilt the 
sub-reflector in order to maximize the sensitivity of the array. It cautions 
with JAO concurrence, however, that it i too late to make major changes 
without incurring unacceptably large cost penalties.

With regard to the exact electromagnetic performance of the two antennas 
and the effects of differences on polarisation and sidelobe performance
 which may be deleterious to mosaicing image fidelity, the Board agrees 
that studies must be performed 
(Recommendation 2). It understands that such a study has recently been 
commissioned by ESO.

Regarding Recommendation 3, that the science IPT continue to work on 
solutions to the potential wide field mosaicing and polarization problems 
posed by different antennas, the Board is pleased to note that this is being 
addressed by a postdoc, hired recently by NRAO.

The Board has reacted to the ASAC\u2019s worries (Recommendation 11) about 
the need for a serious, integrated outreach programme to \u201censure that 
ALMA has a single public face\u201d by asking the JAO to present plans for 
such a programme to the Board\u2019s June meeting.

More broadly, during informal discussions in Kyoto Board members acknowledged 
the critical importance of ASAC in effective ALMA communications within the 
community of professional astronomers, in at least two ways over and above 
the formal reports. First, whenever opportunities arise with professional 
colleagues ASAC and Board members alike need to share accurately their 
excellent, detailed understanding of ALMA developments and the efforts 
being made by the partnership to deliver this ambitious, complex, pioneering 
facility. Second, both ASAC and Board members need to promptly and 
effectively correct misinformation arising within the professional community 
that comes to any member\u2019s attention. Sharing an enormous stake in 
ALMA\u2019s success, we all have a responsibility to ensure that astronomers 
worldwide are well and accurately informed.

Once again, the Board is sincerely grateful to the ASAC for their hard work 
in carrying out their charge. We thank Christine Wilson for her work as 
chair and congratulate her on an excellent presentation of the ASAC report, 
and look forward to working with John Richer as the next ASAC Chair. We 
request that future ASAC presentations include some brief material with 
recent science results (for example, as relevant to the ASAC charges).