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The NexStar User's Guide II - Excerpt from Chapter 5

GoTo Approach

GoTo Approach is used to minimize the effects of gear backlash. On the NexStar+ and NexStar version 4 hand controls, press MENU, scroll to Scope Setup and press ENTER, then scroll to GoTo Approach and press ENTER. On the StarSense hand control, press MENU, scroll to Telescope and press ENTER, scroll to Setup and press ENTER, then scroll to GoTo Approach and press ENTER. Both axes, altitude and azimuth, can be set to either Positive or Negative. Altitude Positive means the final approach will be with the front of the scope moving up; azimuth Positive indicates the front of the scope is moving to the right, both as viewed from the back of the scope.

One caveat, at the time of this writing, changing this setting in the StarSense hand control has no effect; the scope always uses a positive GoTo Approach for both axes.

As noted in Chapter 4, when centering stars during the alignment process (next section), final motions must match the GoTo Approach. In other words, if the front of the scope is moving up (positive) and to the right (positive) at the end of a GoTo, you must center the alignment stars with the front of the scope moving up and to the right. Since the up/down arrow buttons are normally reversed at rates 1 through 6, that means your final centering motions must be with the down and right arrow buttons.

At the time of this writing, the default settings of the NexStar+ and the SkyPortal app are negative for altitude (up/down). The default settings for the NexStar version 4 and StarSense hand control are positive for altitude. When used in alt-az mode (no wedge), back-heavy scopes perform best with this set to positive while front-heavy scopes should have it set to negative. This helps to minimize the effects of gear backlash on GoTo accuracy. On a wedge, GoTo performance is not affected by this setting.

For all types of hand controls and in the SkyPortal app, the azimuth GoTo Approach defaults to positive. This is correct for the Northern Hemisphere, but in the Southern Hemisphere, change the azimuth GoTo Approach to negative. The correct setting per hemisphere ensures the final motion during a GoTo matches the tracking direction of the majority of celestial objects in the sky. This allows tracking to start immediately without delay caused by gear backlash and also provides correct coordinates if an external device (computer, tablet or smartphone) queries the scope.


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