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GBT Traditional Pointing Model
Currently the traditional pointing model used at the GBT consists of 8 physical terms. The M&C system corrects for these errors in the form of a two-dimensional Fourier series. The azimuth and elevation series can be expresses as a summation over the indices p and q,
f(A,E) = a(p,q)*Sin(pA)Sin(qE) + b(p,q)*Cos(pA)Sin(qE) + c(p,q)*Sin(pA)Cos(qE) + d(p,q)*Cos(pA)Cos(qE)
where A is azimuth and E is elevation. In the control system all
terms share a common input position (i.e., the terms are parallel).
Last modified: Thu Oct 24 10:21:29 EDT 2002
| Azimuth Pointing Terms (DeltaA*Cos(E)) | |||
|---|---|---|---|
| Harmonic Term | TPOINT Term | Functional Form | Physical Meaning |
| d0,0 | CA | 1 | Horizontal Collimation |
| b0,1 | NPAE | Sin(E) | El Axle Collimation |
| d0,1 | IA | Cos(E) | Az Zero |
| b1,1 | AW | Cos(A)Sin(E) | Zenith E-Tilt |
| a1,1 | AN | Sin(A)Sin(E) | Zenith N-Tilt |
| Elevation Pointing Terms (DeltaE) | |||
|---|---|---|---|
| Harmonic Term | TPOINT Term | Functional Form | Physical Meaning |
| d0,0 | -IE | 1 | El Zero |
| c1,0 | -AW | Sin(A) | Zenith E-Tilt |
| d1,0 | AN | Cos(A) | Zenith N-Tilt |
| b0,1 | HZCZ | Sin(E) | Asymmetric Gravity |
| d0,1 | HZSZ | Cos(E) | Symmetric Gravity |
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