Target significantly off after meridian flip

Hello,

Gunning M 64 for the last 2 nights, I faced the same issue each night for no obvious reasons: it seems that after flipping the mount, the target is off, by several minutes.

My setup: SGP pro, PHD2, Celestron C8 HD, autofocus through OAG, Mach 1 mount; all software and firmware are up-to-date. The guiding camera “sees” very few stars indeed due to the narrow FOV and relatively low star population in that area. Plate solving works well.

Any idea of what I should investigate?

Thanks!

We’ll need logs to investigate. Are you using auto center?

Thank you,
Jared

Hi Jared, yes, autocenter applied.
It appears to me as if that setting was ignored altogether:

image
Logs are available here:

Thanks!

Hello again
I confirm: Meridian flip seems broken in the latest version. :angry:

I shot M51 yesterday evening and faced the same problem: after flipping, the target is lost: DEC is off by 1 degree - see screenshots below, before and after flip.

Log file “sg_logfile_20200403194425.log” is stored in the same shared foler as in my previous message.

Plate solved image BEFORE meridian flip:

image

Plate solved image AFTER meridian flip:

image

Thanks.

Thank you for looking into it.

Please also read my latest post: same issue on M51 yesterday night, not sure the flip occurred under the pole

Thanks and good luck :four_leaf_clover:

KR

Rodolphe.

There are a bunch of logs there… not sure which one(s) show the issue or the approximate time, but I will say that there is a bug that could consider a valid blind solve after flip as invalid causing abort. That will be fixed in the next release. If that’s not what is happening please help us narrow the logs and we’ll take a look.

Hi Ken

Indeed not easy to identify the right logs. I just copied those where the issue was observed. This they should all be relevant.

However, I stayed close to my computer until 3 AM this morning to understand what was really happening. I found that after flipping theplate solving happened as expected and was able to recentrer correctly. What failed is the guider:
it couldn’t find a suitable star in the field and was thus failing. Recovery thus triggered. I slightly moved the target to find a valid guide star and all went swiftly afterwards.

In summary, I don’t think SGP is buggy. The narrow imaging field of my setup combined with a region of the sky featuring only few stars seems to be the root cause of the problem.

Time to consider using a field rotator?

Anyways, thanks for looking into the issue.

Stay safe :slight_smile:

KR

Rodolphe.

Ah yes… narrow field imaging is not for the faint of heart.

Had another run last night, on M109 this time. All went well, I was lucky enough that PHD2 could find a suitable guide star after the flip.
Thanks Ken for your insight.