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Appendix A -- HUT Mirror MotionsHUT primary mirror motions are used to focus the telescope, and can also be used for offsetting or performing a raster pattern of motions. Three motors (one on each of the support arms of the primary) are used to move the mirror: all three are moved in the same direction and at the same speed to accomplish focus activities, while various combinations are used to perform offset or raster motions.
The time necessary to move the mirror for various activities can be estimated with the following approximate formulae:
Equation 7
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Equation 7
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where \(*D\(*h is a desired angular offset in arcsec, and \(bv\(*DX \(bv is a focus motion in \(*mm.
To perform a raster pattern, one specifies a number of parameters in a sequence load as follows:
Zcount = # of rows in pattern \(mi 1 Ycount = # of points in each row \(mi 1 dZ = step size in Z direction, in arcsec dY = step size in Y direction, in arcsec Interval = nominal time spent at each dwell point, in secondsThe time to perform a raster can then be estimated as
Equation 7
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Equation 7
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Equation 7
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An example raster pattern is shown in Figure A1.
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