Z shaped stars!!

[Rustysplit]

Evenin' all.

I have been playing with the alignment of my neq6 tonight using the new 3.28 beta synscan polar realign.I thought I would test it out on some unguided subs just to see how accurate or not it was.

First I tried 2min subs on procyon, fairly close to the celestial equator I think, I ended up with Z shaped star trails, very small but there nonetheless.Also tried near the pole and ended up with same effect just on it's side.

It seems to me that this can't be an alignment issue as the effect is there at both locations to the same degree, so could it be the gearing in the mount?? Anyone else had this??

Alan

[Shibby]

Hmm, I think that if you only have the ra motor running, the only explanation i can think of is periodic error combined with drift due to misalignment. You should expect better than this from your mount so something is untoward...

[Rustysplit]

That was my thought at first Lewis, but I let the camera run for around 10 subs in each location, and each sub showed the same. Surely periodic error can't be that bad across the whole gear!!??

[ollypenrice]

Uncorrected PE on the NEQ6 is huge. Its virtue is that it generally guides out well.

I agree with Lewis that a PE superimosed over a polar misalignment is the best fit with your observation.

Did you check the orientation of your polarscope?

It's hard to tell without more info but really unguided long exposure imaging comes in when you buy a Paramount, a 10 Micron, an AP, etc, and use them at short focal lengths. (Would you do that??)

Olly

[Rustysplit]

I should explain a bit more. I normally use a synguider and st80 combo on my 200p when imaging.

I took these just out of curiosity to see how good the synscan polar align routine worked. It appears not that well!! What shocked me was the z shape. I was fully expecting trailing, but not Z's

You are right Olly that the eq6 guides well. I think I will stop looking at stuff out of curiosity, and just get on with it!!