Hi.

Does anyone know how well autoguiders (201 XT, ST-4, 208XT, 216XT, ST-7/8
and others) work in
alt-az mode.
I ask this because in alt-az the moves (angles) required for a given
correction change during exposure, and I think the autoguiders use initial
setup values.
Can the autoguiders adapt themselves during the exposure ?

The case is the autoguider is placed after the derotator and so rotates
relative to the scope mechanical axes.
Lets suppose the guider is placed to start aligned, that is the x pixel
lines are aligned with one mechanical axe and the y pixel lines are aligned
with the other mechanical axe. In this way if the autoguider detects a
drift along one of its pixel lines it will try to correct it only with one
motor. Now, as the autoguider rotates relative to the scope the alignement
changes, and to correct a drift along a pixel line it will have to move
both motors.
I dont know if the autoguider is prepared to deal with it. Does anybody
know ?

Pedro Santos

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