SGP Auto Meridian Flip Failing


Hello Everyone.


I had and an issue with the Auto Meridian Flip in Sequence Generator Pro (SGP) failing with the Mach1 and new version of APCC PRO (v1.5.0.12) during my last imaging run. I think it is related to the new Homing/Limits that I have set in APCC. Currently the RA Limit is set to 0 Mins from meridian and my Dec Limit is set to -60.55 Degrees. If the mount hits these limits I have it set to Stop Slew and Tracking.


My guess is that I am hitting the RA limit before SGP gets around to issuing the Auto Meridian Flip slew command which is causing the flip to fail because slewing has been disabled by APCC. I could disable the RA Limits, but I would prefer not to because I kind of like the peace of mind of having it enabled. The other option would be to put in a negative amount in the RA Limit, e.g. -20 Mins from Meridian and this hopefully give SGP enough time to perform the Auto Meridian Flip before it hits the RA limit. However, I am not sure if this is allowed by APCC.


I would be very interested to hear what other folks who are using SGP and have set Homing/Limits in APCC and what they have done to resolve this issue.


Thanks for the help.


Andrew J


Hi Andrew,

SGP won't allow negative meridian delays. pretty much all you can do is set SGP's meridian delay to zero, or some positive value less than the earliest time past the meridian that APCC would stop the mount.

if like me you have a few places where APCC's meridian limit is before the actual meridian, you're stuck. you either have to not image targets at the corresponding declinations, or schedule them such that the telescope points at them from the east side of the pier (that is, the targets are scheduled such that they run after they cross the meridian.)

as part of the discussion about this on the SGP forums, there was talk of adding some new stuff to ASCOM that would let a mount control program ask the mount what it thought it's meridian limits are. if that happens and APCC/SGP support it then we'll be golden. but it's probably not happening anytime soon.

SGP probably needs some improvements in the meridian flip category as well - for instance right now it seems to need to let the mount track past the meridian to detect that a meridian flip is possible. obviously that won't work if the mount needs to stop before the meridian is reached.



Hi Rob.

Thank you for the update. It is good to know it was not just me being stupid and setting something incorrectly. I actually don' think it is the meridian delay that is causing the issue in my case as I normally don't need that as I have setup meridian limits which are all > then 40 mins past the meridian which should be plenty of time for SGP to determine it needs to do a flip. I think my issue is I am using the RA Limit on the Limit/Homing tab in the latest version for APCC. That is currently set to zero and it would appear in the race to zero between SGP and APCC, APCC is winning and stopping the tracking before SGP has a chance to trigger the flip. I may try tweaking my RA Limits to be closer to my meridian limits, i.e. around -40mins, and see if that helps.

Thanks again.

Andrew J