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Meridian Flip and the Sequencer

Posted: Wed Nov 24, 2021 9:40 pm
by Desbarry
Sorry for maybe a dumb question. Ive never done a meridian flip while imaging. My rig is now on a pier and having shorter refractor ota;s hasn't really been an issue. However is the only way to do this by checking the boxes in EQMOD and checking "limits" ie the mount will know its approaching the meridian and alert me. Is there a facility to do this as part of the sequencer in Sharpcap 4? I can now dither but maybe now is time to look into this meridian flip issue incase I buy a longer scope in the future?

Best wishes Derek PS I use Cartes Du Ceil EQMOD ASCOM via laptop.

Re: Meridian Flip and the Sequencer

Posted: Thu Nov 25, 2021 10:31 am
by admin
Hi Derek,

there isn't an easy way (yet) to do this, but there is an option to try to build this with the sequencer...

In the advanced steps list, there is a step called 'Stop running these steps when <X> degrees from the meridian'. If you put your initial captures inside that step then SharpCap will capture until nearing the meridian. Then, after that block, put something like

* Stop guiding
* Wait the right amount of time for the mount to actually get to the meridian
* Re goto the target (should flip the mount)
* Re plate solve/sync to center the target
* start guiding again
* start capturing again

I know all the steps work individually, and it's how I plan to start putting together automatic meridian flips when I get time, but I have not tested them all together yet.

Since the time taken to move 1 degree in RA is 4 minutes, you should make sure the distance that you stop before the meridian exceeds 4 * (your exposure length in minutes) - otherwise there may be a frame starting before the threshold is reached that is still in progress at the meridian. So, for instance for 90 second exposures you could set 0.5 degrees which will then stop the imaging the first time a frame finishes after 2 minutes before reaching the meridian.

If your mount can track past the meridian then you can enter a negative value, so for instance -8 would let imaging continue until 8 degrees past the meridian.

Hope this helps,


Re: Meridian Flip and the Sequencer

Posted: Thu Nov 25, 2021 4:18 pm
by Desbarry
Thanks Robin, if you have plans to eventually build this into the sequencer then I will probably just wait till you release the new version with this as an option. Its not a big deal at the moment as I still babysit the mount outside but if I eventually get an obs built its something I would like to enable and go for a coffee etc

Best wishes Derek