Sensitivity Loss versus Duration of Reconnguration and Alma Array Design

The analysis of e ective time loss during recon guration by Guilloteau (1999) is re-examined for the robustness of his conclusion that the time loss is minimized by moving only a small number of antennas each day. I am able to reproduce this analysis and found that this conclusion is independent of the assumptions on antenna move time and the length of post-move calibration. I nd, however, this optimization to compete against the total duration for recon guration, which is a serious concern for the recon guration to and from the largest con guration. A more fundamental problem is that this concern over recon guration e ciency is dwarfed by the concern over observing efciency in most cases, as previously shown by the cost-bene t analysis by Holdaway (1998) and by Yun & Kogan (1999). A stronger case will be made if such a gradual recon guration scheme can be shown to achieve a high observing e ciency as well.