PARTICLE PHYSICS AND ASTRONOMY RESEARCH COUNCIL MTPPN /5.1
JOINT ASTRONOMY CENTRE

James Clerk Maxwell Telescope

JCMT Pointing Project Note 5.1

The JCMT track, 1995 :
Analysis of pointing errors, and implications for proposed engineering work on the track

• Contents
• Introduction
• Geometric basics and assumptions
• The Pointing Error Budget
  • Mechanical hysteresis, e
  • Antenna construction errors, e.
  • Encoder resolution, e.
  • Thermal Effects, e
  • Telescope tracking, e
  • SMU & TMU alignment
  • Instrument alignment
  • Signal-to-Noise ratio of pointing measurement, e.
  • Pointing logging.
  • Atmospheric seeing conditions, e.
  • Summary
• Desiderata for the production of the track model
• The experiments
  • Standard Inclinometry Configuration.
  • Repeated Inclinometry
  • The Overlap region
  • Hysteresis
  • Roll : Derived from A-frame Inclinometry
  • Track profile
  • Direct inclinometry of the track profile
  • Leica (optical laser ranging) measurements of the track profile
  • Joint Steps
  • Radial-Arm Inclinometry
  • Inclinometry and Pointing with Shims on the track
    • Wheel motion to A-frame tilt
    • Wheel motion (Right A-frame) to PITCH and ROLL
    • Pointing errors
    • Elevation Pointing Errors
    • Azimuth Pointing Errors
  • `No-track' pointing and tracking
  • Tracking over joints at high azimuthal resolution
• Assessment of Track Errors
• Discussion
• Acknowledgements
• Appendix A - Antenna Azimuths of Wheel-Joint Interactions
• Figures & Captions
• About this document ...