FIGURE 6. Telescope Offset Conversions (ignoring on-sky scaling issues)
FIGURE 6. Telescope Offset Conversions (ignoring on-sky scaling issues)
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Telescope offsets can be requested in any one of the instrument, TV, (Az,El) or (RA,Dec) coordinate systems. Offsets in any of the first three systems are converted to (RA,Dec) offsets before being applied.
See Telescope Offset Conversions (ignoring on-sky scaling issues) shows a flow diagram of the conversions. This corresponds directly to the DCS offsetting code except that the issue of whether coordinates are "scaled" on the sky (which introduces cos(El) and cos(Dec) terms as mentioned in See (Az,El) Coordinate System ) is ignored.