GEM flip with Sitech controller

[William Bristow]

William, is your colleague able to image through the meridian and does the mount flip at the first slew after the image is finished and the telescope is pointing past the meridian?
Or is he using those settings only to postpone the flip until 10 degrees past the meridian and pauses or stops imaging at that moment?
Thanks.

Hi Albert.

Yes, with SGP the MESU does image through the Meridian limit by the amount you set in SGP 'Meridian Flip Options'.

My colleague has normally set 'Minutes Past Meridian to Flip' = 5 and 'Wait For Meridian' is ticked, as in the following screen capture:

Meridian Flip Options.jpg

What will happen if you have a sequence of 10 minute exposures that cross the Meridian?

With the above options set if a sequenced exposure is due to start less than five minutes before the meridian then SGP will wait, the mount will continue to track until the meridian is reached and then command the mount to flip, then it will plate solve, center, start guiding and continue with the acquisition sequence.

If the sequenced exposure is due to begin more than five minutes before the meridian limit then the exposure will begin immediately because SGP can see that you have allowed 'Minutes Past Meridian To Flip' = '5 Minutes'. When the exposure is complete then SGP will command the MESU to flip and continue the sequence.

This does mean that you can have a 'dead' time of up to five minutes as the meridian is reached but you can play with the Meridian limit settings in the Sitech and the Meridian Flip Options in SGP to shorten (or lengthen) the 'dead' time at the meridian, it just depends where your collision points are etc.

Interestingly, my colleague mentioned that Lucas Mesu asked for those separate Over-Pole \ Under-Pole Meridian limits to be introduced to the Sitech driver, they did not feature in earlier versions of the driver. We think it was introduced to accommodate side-by-side OTA's where one OTA was much bigger or longer than the other and it would hit the pier earlier depending which side of the meridian the mount was on.

Lastly, my colleague said, very important, the usual reason that a pier flip does not happen is when you forget to tick the box 'Use Auto Meridian Flip' on the Telescope Options / Data tab in SGP setup. The 'Meridian Flip Options' tab is accessed by clicking the 'Set' button on that 'Telescope Options / Data tab in SGP as in the following image:

Telescope Options.jpg

My colleague also pointed me to a how-to video showing set-up of Auto Meridian flip with SGP / PHD / MESU, it might be useful, I don't know, but here is the link to the video:

https://www.youtube.com/watch?v=LAjTZnL8pHQ

Hopefully the above will make things a bit clearer but how you transfer this to ACP I have no idea. My Paramount - ACP setup was a walk in the park compared to the Sitech and the MESU. I guess it's because there are so many different options in Sitech setup that it's difficult to see how it all integrates with the command program.

HTH.

William.