Disappointing Ha result on Pacman

[AKB]

Ah, I think I'm getting somewhere, although I'm not sure WHY...

FOUR clear nights in a row – am I dreaming?

Anyway, here's another attempt on the pelican, exactly the same setup as before EXCEPT that I've changed from the Baader 7nm 2" to a 1.25", which I happened to have.

So I've no idea whether this is the filter, or just the conditions which did seem to me to be particularly steady and cloud-free until about midnight.

@carastro – I have taken some 10 minutes subs, but will post separately if the results are an improvement, since I think I've drifted too far from the original topic (the Pacman!)

[AKB]

Reverting to the original problem target, I've tried again.  A bit less moon, of course, but longer and more subs: 12 x 10 minutes.  Also still using the 1.25" filter, so have yet to compare with the original 2" problem one.

Anyway, I think this is progress, although it was done in haste – no refocus from previous night.  Eggy stars are back, I'm getting big spikes in both RA and DEC, about every 8 minutes or so.  Really confused about how this is happening.

 

[tooth_dr]

That’s really nice, much better. I actually have done the same. Now have a few 10 min subs compared with 5 minute ones and with a bit less moon. 

[carastro]

MUCH better.  Not sure about the eggy stars, is there by any chance some flex between the guide scope and imaging scope?

Carole 

[Stub Mandrel]

53 minutes ago, AKB said:

Eggy starts are back, I'm getting big spikes in both RA and DEC, about every 8 minutes or so.  Really confused about how this is happening.

The seeing and guiding here was awful last night.

[AKB]

46 minutes ago, Stub Mandrel said:

The seeing and guiding here was awful last night.

Thanks for that.  Yes, may be part of the problem...

50 minutes ago, carastro said:

is there by any chance some flex between the guide scope and imaging scope?

It's not perfect since I've got guide rings – really need to clamp it down more.  I wondered about the mirror cell too.  I'll get an image of the guide log to demonstrate the scale of problem.

[AKB]

Here's the guide log in question...

There is 10 minutes between each dither, and the vertical scale is +/- 20".

Is it conceivably a cable dragging?  I've tried to tidy up everything as much as possible.  I'm using an Eagle2 attached to the RA arm of the M-Uno mount as a sort of counterweight, but there still has to be one cable, the power, going to it.  In fact, there's also the lightweight cable for the manual guide controls which goes to the mount. Balance is really quite good in that I have no fears about unlocking both axes and pretty much placing the OTA in any orientation I like.  Whilst the mount is tracking there IS only the power cable which needs to move...

 

 

[AKB]

I believe that it WAS a cable problem...

I removed the polar scope and re-routed the power cable through the hollow RA axis, which is one of the features of the M-Uno mount.  Although the seeing tonight was terrible, with a bit of mist and high cloud, it was good enough to try this out, with the following result (to the same vertical scale) with which I'm well pleased.  Playing with the guiding parameters during this time seemed to make really very little difference.  Hopefully, lesson learned and problem solved for good (if that is, in fact, ever possible!)