Report to the JCMT Board - October 2003

Inclinometry
Measurements of the antenna track profile are made every week or so, and have shown no substantial changes during the past 6 months. The generation of hybrid (ClockWise & CounterCW) track models has continued; pointing quality in the north and south are indistinguishable.

Transit step & transit tracking
The 'transit' (elevation motion reversal) problem remains of low practical impact and is effectively corrected within the TCS. The tests ongoing at the time of last writing indicated possible extra drag in the elevation drive, and adjustments were effected. Tracking through transit remains good at levels of 1" rms per hour in each coordinate.

All-sky pointing
All-sky pointing has been substantially stable throughout the period, in terms of both collimations and rms scatters. Values for the latter are 1.5" or better in each coordinate during stable parts of the night. Pointing model updates have become a rarity, occurring essentially only after changes in antenna configuration (eg the SMU R&R). Observers rarely report any general sense that the pointing was 'poor'.

Focus
The July repair to the SMU necessitated a series of zero-point corrections. Corrective algorithms with dependences upon elevation and temperature maintain focusses within 0.1mm rms in Z and 0.2mm in X & Y.

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