Comments on the Canadian Software Proposal (as discussed at last ASAC meeting).

General comments:

• It is at least surprising that this proposal be issued without explicit reference to the considerable amount of work that has been pursued within the ALMA project to define the science based software requirements, in the last 18 months or so. The Science Software Requirements Committee (http://www.alma.nrao.edu/development/computing/workinggroups/ssr/index.html) has widely distributed reports (Alma Memo 293, now superseded by ALMA-Software Memo 11 (at http://www.alma.nrao.edu/development/computing/docs/memos/index.html); they have been submitted to a review process. Requirements have been presented to the ASAC Florence meeting in February. See also ALMA Memo 367.
• This work is continuing by a detailed report on the requirements for the pipeline and for off-line data analysis. A first draft of this is to be discussed at the SSR meeting on July 16/17.
• The software group is taking the stepwise approach to specify the requirements in some detail before making actual implementation choices. Naturally however we have a good feeling on what can be done and what cannot be done in a quasi-real time pipeline, in order not to overspecify the system.
• Given that discussion on pipeline requirements is already taking place within the SSR, we feel that it would be more efficient for ASAC to review our conclusions rather than each committee having parallel discussions that would somehow have to be later integrated.

More specific technical comments will be made by the SSR Committee, let me give a few comments of my own:

• Note that in the requirements document ALMA-Software Memo 11 (Req. 1.0-R7, 6.3-R1) the SSR states that a fundamental requirement for ALMA is that scientifically analyzable images will be automatically produced for observers.
• Our opinion is that the first order feedback on the scheduling should be based on the calibration quality, not on the final images. Hence the separation between the calibration pipeline, the quick look pipeline, and the science data pipeline. Therefore the image processing time scale is not a few minutes, but a few hours at the end of the observing session.
• There is too much emphasis on self-calibration, which will not be feasible for many projects, probably a majority.
• I doubt whether an automatic expert system can be made before any human expertise is obtained on submillimeter image synthesis, especially at the high frequencies. One has to go by steps.

Robert Lucas
(Chair of the ALMA Science Software Requirements Committee)