Star trailing with new Wedge setup. What is the issue? (includes photo)

[evilgeenius]

Hi,

A couple of nights a go I setup my wedge for the first time, it took me a while to get to grips with it, and I still am.

At the end of the night I took a quick 1 minute photo to look at the tracking, and as you can see from the photo, it is completely off.

I still have plenty of things I can do to try and improve this, but I thought i'd just put my first photo up here incase anyone can tell me what the tracking errors are.

The photo shows a stellarium screen grab of m81, including equatorial lines, next to the photo I took. I have rotated my photo so it matches the grab from stellarium in the hope that it will make it easier for someone to diagnose what the issue could be.

I remember reading that the direction of star trails can indicate what type of issue it is, but I cannot remember much more.

My telescope is a Celestron for mounted CPC925.

Any help is appreciated.

Cheers

Chris

[Helen]

Hi Chris,

Here's the help I got when I first started with that wedge. The bit from MartinB is particularly helpful as I bought the wedge off him!

http://stargazerslounge.com/discussions-scopes-whole-setups/56083-all-part-learning-curve-first-light-apt-wedge.html

Helen

[evilgeenius]

Thanks Helen, that looks useful. Next step is to buy myself a Illuminated Recticle.

[Merlin66]

The trailing look to be in RA - tracking rate??

[Capricorn]

Few thoughts:

The scope has a long focal length so any tracking errors will be amplified.

Next how did you polar align the scope? If you pointed the scope at Polaris then the alignment is out as Polaris is not coincident with the axis.

How accurate is the wedge set for your latitude.

[ollypenrice]

The combination of wedge and long focal length is infernally intolerant. If your setup is not permanent then forget wedges, they take too long to align accurately.

Use a drift alignment method, of which there are many on the net, then pay careful attention to balance.

Olly