ALMA Science Advisory Committee Teleconference 11 December 2000 Draft Minutes Participants: J. Baars, R. Bachiller, R. Booth, L. Bronfman, R. Crutcher, D. Emerson, S. Guilloteau, M. Gurwell, T. Hasegawa, M. Ishiguru, H. Matsuo, K. Menten, N. Nakai, M. Rafal, J. Richer, S. Sakamoto, P. Shaver, E. van Dishoeck, W. Welch, C. Wilson, A. Wootten 1. Minutes of last Teleconference The minutes of the last teleconference were accepted. 2. Nominations for Japanese members of the ASAC The following members have been proposed from Japan: Yasuo Fukui (Nagoya U.) Tetsuo Hasegawa (NAOJ) Hiroshi Matsuo (NAOJ) Naomasa Nakai (NAOJ) Seiichi Sakamoto (NAOJ) Ken'ichi Tatematsu (NAOJ) Masato Tsuboi (Ibaraki U.) Satoshi Yamamoto (U. of Tokyo) Ryohei Kawabe is to stay on as an ex-officio member 3. Feb. 23-24 Face-to-Face ASAC Meeting in Florence All ASAC members were encouraged to make their reservations for this meeting by December 15. M. Walmsley will provide a list of those who have registered for the meeting. Other meetings in Feb-March were also mentioned. S. Guilloteau expects several participants from the ASAC at the Configuration PDR in Grenoble on 26-27 Feb. Results from simulations and imaging studies will be available. It was commented that operational studies should also be done in preparation for that meeting. 4. Reports on the Antenna CDRs J. Welch and J. Baars reported on the recent antenna CDRs. There was a brief discussion about the possibility of optical guiding. J. Welch commented that it could provide at least an important backup, particularly for night observing at the highest frequencies. The possibilities and constraints of using the 12m mounts for the compact array antennas were also discussed. 5. Polarization R. Crutcher expressed concern that not enough attention is being given to polarization requirements. The difficulties of compatibility between the polarization requirements and other constraints of ALMA were mentioned by S. Guilloteau and others. On a proposal by R. Crutcher, the following resolution was agreed: “The ASAC is concerned that the Project Book does not specifically address how ALMA hardware and software will permit meeting polarization science goals defined by the ASAC. The ASAC believes that a comprehensive solution to enable ALMA polarization should be included expeditiously in the Project Book.” D. Emerson and J. Baars said they would welcome a chapter on polarization in the Project Book. R. Crutcher said he would work on this, and others were encouraged to contribute. 6. ACA Issues The recent memo by J. Baars was briefly discussed. Concerning the possible use of the ALMA mounts for the ACA antennas, J. Baars said that studies and estimates are to be made. J. Welch reiterated that the 6m antennas are an important possibility in order to map the larger scales. For calibration, he suggested the possible use of one 12m antenna as part of the compact array (although the pointing of the 12m antenna would be an issue). S. Guilloteau agreed, but commented that more than one 12m antenna may be needed. 7. Fringe Tracking Centers D. Emerson informed the ASAC that the LO, systems & software groups are considering whether for OTF interferometery the fringe frequency tracking center would be kept constant for the duration for one scan. This would have implications for the realtime software (a great simplification), for the analysis software (a similar simplification), for the potential maximum data rates (perhaps considerably higher), for the maximum OTF field size that can be covered in one scan, and for how OTF interferometry observing to be carried out. The tradeoff between simplification and the higher data rate is an engineering decision. 8. Site Issues R. Booth commented on the Morocco meeting on site testing that took place last month. He said there is still not enough good comparative data on both the Chajnantor and Pampa la Bola sites, although he said that available data indicate that Chajnantor is best. There is inadequate manpower to keep all the equipment running all the time. However, some comparative studies have recently been completed, and in Japan large amounts of comparative data are presently being assessed. It was proposed to discuss this at the Florence face-to-face meeting. The problem of anomalous refraction was discussed, and the possibility of cooled water vapour radiometers was re-visited. D. Emerson commented that in the optics design there was not much space for a cooled 183 GHz WVR. The possible relevance of the CBI data was discussed. In Japan there are plans to re-install a shorter baseline interferometer to measure atmospheric fluctuation power on those scales, which may estimate the anomalous refraction. 9. AOB It was announced that the Atacama Submillimeter Telescope (AST) has received funding approval by the Max-Planck Gesellschaft. K. Menten said that construction should begin as soon as possible; plans call for installation on Chajnantor in late 2002. E. van Dishoeck mentioned the preparation of the European proposal for Phase 2. P. Shaver said that the proposal will be submitted by the end of the year. The science case has been completed, and S. Guilloteau will inform ASAC members of the web site where it can be accessed. 10. Next Teleconference The next ASAC teleconference is scheduled for Friday 19th January at 1515 UT. This is to be confirmed by e-mail.