Report to the JCMT Board; November 2008

Introduction
The good news is that little has changed since the previous report. The bad (frustrating) news is that little has changed since the previous report. In particular, a model of the HARP K-mirror misalignments has vexingly resisted definitive quantification.

Pointing with Receiver A
. . . . remains nominal, with rms scatters in (azimuth,elevation) in the 1.5"-2.0" range.

Pointing with HARP
All-sky pointing with HARP remains comparatively poor. As described previously however, the impact upon science data is defined less by average all-sky pointing statistics and more by the specific errors accrued when changing the K-mirror configuration from the 'AZ/EL' orientation used for pointing (hopefully observers point on local targets before commencing their science) to the 'RA/DEC' orientation used for the science observations. We described last time that a specific assessment of these errors in early 2008 showed mean differences and scatters in (az,el) of (-0.3"+2.0",-0.0"+2.5") and these performances were confirmed in August 2008 in support of one scheduled observing program (m08bu05). We continue to encourage observers to do frequent, local pointing - for this and many other reasons.

Until and unless SCUBA2 demands attention, it remains the priority of the Pointing Project to seek a model for the K-mirror misalignments. The Project is to be lead henceforth by new support scientist Holly Thomas.

Inclinometry
Measurements of the antenna track profile are made every couple of weeks or so, and updates of the track model have been routine and uneventful during the reporting period.

Transit step and central bearing race defect
Neither defect has been characterized during the period, but neither seems to limit the pointing performance.

Temperature corrections & c.
Routine checks are made on the various algorithms within the TCS code relating pointing and focus settings with temperature and elevation. No significant and consistent changes have been noted during the reporting period.