Flip Angle – The “Flip Angle” setting is the amount of degrees, before and after the meridian where everything in-between is known as a flip zone. When the limit is reached certain actions can be taken on the main menu under Axis Limits such as Do Nothing, Stop Tracking, Park, or how log to track after reaching the flip angle. Each degree equates to about 4 minutes of sidereal tracking time. The default setting is 20 degrees, so this means the flip zone is 40 degrees total, 20 before the meridian and 20 degrees after the meridian.
Imaging Applications – Applications like NINA or SGP can take advantage of flip zone by forcing the flip using the “Side of Pier” command before or after hitting the meridian. It’s recommended that the flips occur well before hitting the Flip Angle setting. This way the limits can be used as a safety factor and an action can be taken if the flip failed from the image acquisition application. Applications like Voyager use the “Destination Side of Pier” to determine when a flip can occur. Basically it ask GSS if a goto was executed what side of pier the mount would end up on. Based on this Voyager would test the targets coordinates to see if a flip can occur. To properly accommodate applications that use a goto, set the Flip Angle to either a setting of 0 or 1 and the Axis Limits to “Do Nothing”. Then tell the application to wait a number of minutes, typically 1-5 minutes after passing the meridian to test for the flip. If the flip fails then the “Tracking Limit” will be hit and the action selected will be taken.
GoTo and Slews – The “Flip Angle” also affects gotos and slews. Any target within the flip zone can be pointed at by either side of the pier, that’s the purpose of the zone. To determine which side of pier takes action depends on what side is closest. i.e. Say you’re pointing east and about 45 degrees in altitude and you want a target that is 5 minutes passed meridian. Since the target is in the flip zone and the mount is in the pier west configuration the slew will not flip the mount because the axis is closer on the current side. If the target was passed the flip zone then an automatic flip would occur since that’s the only pointing state that will work.
Additional Help – Additional help videos that explain how flips work, “How to Flips” and “Flip Angle Gotos” are available here.