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Introduction

The pointing performance of the JCMT is currently good, with r.m.s. errors in each axis of less than two arcseconds being achieved on a good night. It is generally agreed however that excellent pointing is a high priority for the JCMT. At the highest frequencies, offsets of more than half a beam-width will not be uncommon unless the rms pointing error is of the order of one arcsecond or less. The fact that the telescope can already get close to this under the best conditions means that expecting such performance is not unrealistic -- indeed the problem with the JCMT pointing at present is that the best performance which the telescope is capable of is not routinely achieved.

In order to reduce departures from the best possible performance, we propose to make it a firm goal of the JCMT to aim for consistently good pointing. Specifically, we should expect that pointing offsets should routinely have a normal distribution with a mean of zero and a standard deviation of one arcsecond or less in each axis, for all positions of the telescope, day or night (weather permitting). Failure to achieve this performance should be consider a "fault", and require a positive response.

To achieve this aim we will require effort from all groups: mechanical, electrical, software and commissioning support, and this work will have to be given a high priority. This intent of this document is to give a broad overview of how we intend to achieve this goal, identifying the main items of work involved, and placing these in priority order.



James B. Scobbie
Wed Nov 8 10:57:48 HST 1995