Pickerings Triangle Ha

[ApophisAstros]

Capture details on Astrobin
https://astrob.in/pib7wd/0/
Roger

[Carole]

It's come out quite well.  I haven't yet managed to get a decent image of this target, I think it is a bit fainter than the other parts of the Veil.

Carole

[RobertM]

A good try Roger whoever, if I may be so bold, I think there's something a bit awry with your setup.  The 120ED should be able to produce good star shapes across the frame with the corrector in place (see what Fay has produced as an example).  Just looking at your astrobin logo it looks like you have quite a lot on top of the 120 and are using the stock thin vixen type dovetail.  If that's the case then I'm sure it's at least part of the problem - the moment of that setup will twist the dovetail and act with the guider to trail stars.  There are only two ways a piggyback setup will work; one is using a stiffer setup ie. Losmandy type dovetails, the other is to have a lightweight setup on top.  There isn't enough definition to see much else.

PS if that isn't a current picture of your rig then apologies 😎

Edit: I'm not sure why your NGC6946 image isn't showing those artefacts 🤷‍♂️ if imaged on the same setup.

Hope that helps
Robert

[Carole]

I hadn't zoomed in and noticed the stars.  To be honest, it looks more like field rotation to me as the corner stars are elongated in a rotational sort of way, but the middle is OK.

I am pretty sure I have read that incorrect PA will cause this, but Roger has Polemaster, is it possible PA could have slipped afterwards?

I have to confess that my dual rig is very similar to Roger's using piggy back on a vixen dovetail, but I don't have such a problem, however I don't have such a large scope as the ED120 as part of that set up.

Carole

[ApophisAstros]

Think you're right Carole as an Oiii sub from 2 days before(same setup) is ok, so i assumed i lost PA for pickerings,

1 x 450s Oiii sub
Roger