Meridian flip questions

[Moonstruck]

Hello,
I have an EQ6 and an EQ8 mount and use EQMOD. I have run into a couple situations with my EQ6 where the camera has hit the tripod leg during all-night imaging, and I want to avoid that in the future. From what I have heard the best way to do that is to either set limits on where the scope can slew (in EQMOD), or use EQMOD's auto meridian flip feature.

If I use EQMOD's auto meridian flip feature, will the mount automatically do a meridian flip, then re-align on the target exactly as it was before the flip? Or do I need to program Sharpcap (through the sequence planner) to move to the position it was before the flip and plate solve so that it is in the right spot? If I need to use Sharpcap are there instructions somewhere with meridian flip commands to program into the sequencer?

If you can give me some guidance on how Sharpcap and EQMOD need to work together for meridian flips (if indeed they need to) I'd appreciate it. I have been avoiding the subject of meridian flips thus far as they appeared to be complex, but maybe I am mistaken. I think I will need to learn this though to prevent camera/tripod collisions in the future.

Thanks!

[admin]

Hi,

I don't think the auto flip option in EQMOD is going to be much help - from the documentation it looks like it will simply perform a flip when the tracking reaches the meridian. SharpCap won't know anything about the fact that this is going to happen, so at the least you will get some frames of trailed stars during the flip. What's worse, unless your mount hits GOTO targets perfectly on both sides of the meridian, you will end up pointing in the wrong place after doing the flip.

You should however turn on the meridian and horizon limits in EQMOD to prevent the mount from moving into dangerous positions - I think you can configure so that tracking is allowed for a certain distance past the meridian (1 hour is often safe).

A far better approach is to work in the sequencer to get the flip to happen, a rough outline of what you need to do is...

* Wrap the imaging steps to happen before the meridian in a 'Stop running these steps when <distance> degrees from the meridian'. Say you set 1 degree, that will stop running the imaging about 4 minutes (time wise) before the mount reaches the meridian

* Add a delay at this point so that the mount tracks to the meridian for the remaining ~4 minutes

* Add a 'Meridian flip the mount' step - that should bring the scope to the other side of the pier

* Add a step that does a GOTO back to the target to ensure that the co-ordinates are correct

* Add a 'plate solve and resync' step to center the target

* Add a duplicated block of steps to perform imaging after the meridian flip

This is something that may need to be customized and tweaked based on your setup - probably worth picking a target that is only maybe 5-10 minutes from hitting the meridian and try the sequence on that to see if everything works, then tweak and retest until it all runs to plan before trying any real targets.

cheers,

Robin

[Moonstruck]

Thanks very much for the help and instructions. I appreciate it!