Vixen AGA-1 - Manual (Page 13)

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Ⓔ Starting astrophotography
It is now ready to start astrophotography.
The auto-guiding will continue until the “Pause” key is pressed or
the guide star is lost.
If you press the “Pause” key, the auto-guiding will be discontinued.
To restart the auto-guiding, press the “Guide” key.
If the guide star is lost by going behind the clouds, the mode
indicators of the Level Check, Guide and Pause will begin to blink
red to indicate a guiding error, and the autoguiding will be
discontinued.
In case of such a guiding error, you cannot restart the auto-guiding
by pressing the “Guide” key.