Summary

The major limitation in the accuracy of the single dish mode will be due to differential spillover in the ``on''-``off'' comparison. It is difficult to know in advance whether the nodding secondary or the OTF scanning scheme will be more plagued by this. The antenna background is likely to be of the order of 10K. Whether the modulation of this by the moving secondary or scanning across the ground is worse can only be determined by experiment. Thus, it will be important that the prototype antennas be equipped for both kind of observing and tests be carried out. Both good gain stability and chopping secondaries must be installed. It may be possible to test these options on existing systems. It may also be possible to test further the ``homogeneous array'' operation (array with single dish one of the array antennas) using one of the existing antenna systems. Another activity that would be important in the near term would be to test the calculations of HOE with atmospheric data taken at higher frequencies. The atmospheric conditions on Mauna Kea are probably close enough to those at Chajnantor that JCMT observations would be useful for this. Among all the possible methods to obtain the total power data for the array, the OTF scheme is the simplest and least expensive, and it appears that it should work. The main requirement is a fractional receiver gain stability of about 1 x 10^-4 in a one second time interval for all the antennas. There should be no difficulty in achieving this.