Centreing failure at step 3


Hi all,

Last night i couldn’t get past a failure to slew at step 3 whilst platesolving. Previously It’s all been working reasonably well and solving fine. I haven’t made any changes.

here’s a link to log file


thanks for any help with identifying the problem which was a showstopper.

I am set up with platesolve2 as main solve and ANSVR as failover. Result was same with both. Solves fine but fails at step 3

Just to add I was using ‘Centre Now’ to position the scope on the target before starting the sequence. This is my normal process when the unusual event of ‘clear sky’ happens and usually works fine.

best wishes


Right… when you haven’t made any changes, the issue is almost always related to a specific target. In your case it’s this:

ASCOM Telescope: Error in Slew : SiTech Says: InvalidOperation Slew Requires Meridian Flip! (ASCOM.InvalidOperationException: SiTech Says: InvalidOperation Slew Requires Meridian Flip!

Your mount is actively refusing the slew command because it thinks it will need to flip in order to point to the requested location.

SGPro cannot do anything about this, but we do need to handle this particular error more elegantly. I’ll look into that.


ok thanks for your help with this Ken. Perhaps there’a a sitech setting I can change and I’ll ask the sitech folks.
Meanwhile if I get the error again I can flip manually and try re centereing.


Error handling for centering has been improved a bit starting in It now uses the new-ish sequence level notifications area (exclamation icon in the targets list) to convey more specifics about what happened during centering. In this case it would have logged a user facing error saying:

Slew failed! InvalidOperation Slew Requires Meridian Flip!

Many other areas were also updated to improve the quality of feedback.


Thanks Ken - this is helpful especially when you’re out there in the

Best wishes