开云体育

On Mon, Aug 26, 2024 at 08:05 AM, WayBack wrote:

On Sun, Aug 25, 2024 at 10:04 AM, Ed Harp wrote:

by spirit level, I would guess you mean the "CWD"

Yes, just some best practice thoughts. ?Aligning the four G11 mount spirit levels sets the mount into a mechanical position that corresponds with the initial Gemini-2 encoder position. ?The starting physical orientation of CWD and the corresponding controller state, a Cold or Warm Start, are synchronized through the encoder values. ?The simplest method involves setting the mount to CWD while powered off, and once Gemini-2 is powered on and passes the Cold Start, tracking begins. Other startup sequences just need to consider the end goal. ASIAIR expects the mount to be operational, similar to other controlled hardware, upon APP connection. If the startup process includes parking the mount, unpark afterwards for ASIAIR. Should the mount require Asmuth rotation for Polar Alignment, it now remain level to maintain accuracy with the encoders. Eventually, the mount will slew to the first bright star for sky alignment, which relies on the precision of CWD. Any movement disrupting the CWD's alignment with the encoders necessitates a return to the leveling process.? It's documented but seems to get lost in the details at times.

??

On the Meridian Filp, that was about a behavior you noted.? The type of OTA and mount set up influences the use.? Scott's enhancements enable the mount to track for hours past the Meridian with the appropriate OTA, which can sometimes eliminate the need for a Meridian Flip.??While the behavior that ASIAIR uses, a Go-To depends on the characteristics of the mount.? If Gemini-2 has two positions it can reach a target, it always does a Go-To to the closest position. ?This can cause the topics to become interwoven.

?

This involves the Limits.? As targets move across the sky, they also traverse over and past the mount's limit points. ?When using a Go-To function for a target on the West Side, ASIAIR requires the target to drift to a position accessible only from the East Side to perform a Meridian Flip. This position on the East Side becomes reachable only when the target moves beyond the EAST Limit and the start of the WGL Limit (the WEST minus WGL position). Both conditions are necessary for the flip.

?

These criteria subsequently affect the limit parameters. If the OTA permits shooting beyond the Meridian, keep the ASIAR delay parameters at zero; it's all about the limits. If the OTA makes contact at or before the Meridian, then delays are necessary to meet the criteria. However, if your OTA target can bypass a Meridian Flip by continuing to track past the Meridian, then disabling it is another excellent option.

?

This can also occur with equipment like a long refractor, where the camera cannot make contact at the northern leg latitudes. In such cases, with relaxed limits and exercising caution it’s possible to track through the meridian too.

?

Doug

?

The Gemini CWD position is simply whatever servo position values are found when Gemini wakes up. A Gemini's initial sky model on boot up always thinks the mount RA axis is perfectly aligned with the NCP, the DEC axis is perpendicular to the RA axis and that the DEC's saddle position is @ 90 degrees. This is why unless the mount is very well polar aligned Gemini's initial GOTOs can be off by widely varying degrees all other setting being correct.? While it is not critical to have a level mount before polar aligning it makes polar alignment much faster and smoother which makes initial GOTOs more accurate which results in smaller correction values to the default sky model.? ?

?

You can save some setup time by having previously set accurate CWD marks on the RA and carefully setting the DEC axis setting circles to 90 degrees and locking them in using the set screws in the DEC setting circle ring. With these marks established you use the built bubble levels in the mount base to level the mount and then set the mount to the premarked positions on the RA and set DEC to 90 using the setting circle ring and etched indicator. No need to go through the bubble level routine on the RA and DEC axes to establish a true CWD before powering up Gemini as it has already been set by using your preset marks.??

?

BTW, never trust the bubble levels on any mount even a Losmandy mount unless you have verified them with a known good digital level or precision bubble level. I have had to replace several bubble levels in used Losmandy mounts I bought or repaired because the vials were no longer properly seated.?

?

To be clear there are no encoders or position switches on Losmandy mount axes or worms. There are encoders integrated with DC motor axels which allow them to be used as servos but these are not normally used by software other than Gemini. This is not to say servo motor position data cannot be used by third party apps.??

?

--