Auto meridian flip?

[stbkaiser]

Hi robin
Last year you mentioned concerning meridian flip:
s. However I am currently adding new steps to try to make this a bit easier.
Sooo
Is there a method in sequence to do a automatic meridian flip?
Thanks
Steve

[admin]

Hi Steve,

I did add a sequencer step that should perform the actual meridian flip itself - it will wait up to 15 minutes for the mount to cross the meridian and then attempt to flip the mount over and return to point at the same co-ordinates from the other side.

This was intended to be a building block of more complete flip support (run at the right time, pause guiding/stacking, do the flip, plate solve, resume guiding, etc), but I haven't done that you. Of course you can build all the other stuff in that list from existing sequencer steps if you want. It's something I do intend to return to, but I'm not sure when - any feedback on the current step would be welcome, since the way to get the mount to flip over seems to vary for different brands of mount...

cheers,

Robin

[giraud]

Hello Robin,

I am re-opening this thread of discussion.
I have seen a "Meridian Flip the Mount (experimental)" function. Is it operationnal? And if yes, what subfunctions does it perform and what remains to be customized around it?

Many thanks.
Eric.

[admin]

Hi Eric,

the experimental Meridian flip step performs the actual flip itself (which isn't as simple as it sounds, since the exact commands needed vary from mount to mount).

You should start it within 15 minutes (of time) of reaching the meridian. It will wait for the mount to actually get to the meridian (so that once flipped it will be past the meridian), then it will flip the mount either by setting the side of pier state or by commanding a GOTO that should flip over to the other side.

Around it you need to add

Before flip:
* Something to stop imaging as you approach the meridian - use the 'Stop at <Degrees> from Meridian step' around the imaging tasks before the meridian
* A record of the co-ordinates that you want post-flip. You could use the 'save mount co-ordinates' step or the 'plate solve and save co-ordinates' step.

After flip:
* To goto the co-ordinates after the flip (goto saved co-ordinates)
* A plate solve/resync
* Rotation control if you have a rotator to go back to the original orientation.

cheers,

Robin

[giraud]

Thanks.

No very clear to me how to use the "Stop at <Degrees> from Meridian step' around the imaging tasks before the meridian.

I understand that eveything within this section (so the imaging tasks as you suggest) will stop to be performed. However, I struggle to understand how to handle the command that should then be performed and that otherwise should not. A Kind of IF THEN ELSE.

I also have a question about the Periodic Task related to the Focuser Temperature. Is it periodic in the sense that it is running and checked at all times, independently of where the current step is located within the programme? Or is it just performed as the programme happens to run in the section where the current Periodic Task is specified?

And then have a suggestion: a function that would saveguard the current Wheel Position and another one that would resume this position (like for the camera settings) would be great. Useful for an autofocus process that could be embedded in a section that runs for a given list of filters (I am using a clear parafocal filter to autofocus for my Ha&OIII and SII filters).

Thanks Eric.
Best,
Eric.

[admin]

Hi Eric,

nice idea about saving and restoring the wheel position - I will add that when I have a bit of time

For the 'Stop at degrees from meridian' step, you put everything that you want to run before the meridian inside that step. There are certain points in the running of a sequence that SharpCap will check whether the 'degrees from meridian' threshold has been reached. Once that threshold is reached, SharpCap will stop running the steps inside the 'stop at degrees from meridian' step and move on to the steps after it.

The points where the sequence can be interrupted are

* at the start or end of any step
* between frames in a 'capture still frames' step

Both of these should mean that the sequence should be interrupted in a consistent state (for instance it should wait until the end of a refocus step rather than within it). If we come across situations where it is interrupting a series of steps that have to either all be run or none be run, then I will have to refine.

The periodic refocus on focuser temperature change works in the same way - at each of the interruption points listed above, SharpCap will check the focuser temperature and if it has drifted too far will run the refocus before moving on with the normal progress of the sequence.

cheers,

Robin

[giraud]

Thanks Robin.

I have actually managed to defined and successfully test a Meridian Flip sequence. I have programmed a first sequence to stop just past the meridian (1°), having set before the RA mounts limits about 10°beyond the meridian in EQMOD. I then save the current mount coordinates and apply them again, and as expected the mount performs the meridian flip on its own as it has just past the meridian. Works with my EQ6-R Pro. So I didn't use the "Meridian Flip the Mount (experimental)" function. I attach the .scs sequence (I disabled all the autofocus and guiding routines as the weather doesn't allow much star detection tonight).

However, I am still not sure about the way the "Run a periodic task called <Task Name> when focuser temperature changes by TBD degrees" works. My understanding is that the periodic task actions are to be defined within the box attached to the function. Let's say such a function is included within a "Repeat <Repeat Count> times" sequence, does that mean that the periodic task will apply only within such Repeat sequence, and between critical steps like imaging? And is the reference temperature the one measured at the very begining of the overall sequence (when the RUN button is pressed), or is it redifined when it is called the first time in a given section (like a REPEAT section)?

Best,
Eric.

[admin]

Hi Eric,

yes, a GOTO the same co-ordinates when already past the meridian should do the trick in most cases

More detail on the focuser temperature change...

When the "Run a periodic task called <Task Name> when focuser temperature changes by TBD degrees" is first encountered in the sequence, the current focuser temperature is stored. From then on, each time the sequence moves between steps, or moves between frames in a 'capture still frames' step, the focuser temperature is checked. If the current value differs from the stored value by more than the threshold, the steps inside the periodic task are run. At the end of those steps, the stored focuser temperature is updated and the main series of sequencer steps continues.

This interruption when the focuser temperature changes will continue either until the end of the sequence is reached or you run the 'Stop running a periodic task names <name>' step to cancel the focuser temperature monitoring.

cheers,

Robin

[giraud]

Very clear thanks.

I'll be able to take full advantage of the "Run a periodic task called <Task Name> when focuser temperature changes by TBD degrees" if and when the function to save the current filter wheel position and set the filter wheel position to the last stored position is developped

Cheers,
Eric.

[admin]

Hi Eric,

the good news is that I added those two steps (save/restore filter wheel) yesterday, so they will be in the next update. For good measure, I added steps to save and restore focuser position too, since I expect someone will come up with a use for them!

cheers,

Robin