Simple PA software

[Earl]

I was frustrated with Alignmaster last night as all the other half of the stars it wanted to use were behind a tree.....

So I have been thinking.

My mout auto homes on power on this is set to point at the pole.

Now im pretty certain, if i use a ccd i should be able to overlay a image like that in a polar scope which will scale to match the image, then just pop polaris in the indicated spot.

Any thoughts on this?

[oldpink]

I have similar issues I have the full sky east to west when I look due south
but my house is in the middle of a block that that obstructs my view north up to 60deg

so at best I can choose a "Good" pair to align as any others I can only see one of the pairs
would be better if you could pick your own stars from a list and use them

[bobmoss]

That sounds like such an easy and obvious way to polar align but I've not come across anything that does that. There must be some technical reason why it can't be done.

[Earl]

I dont think it will ever be as accurat as a good drift procedure, but its gota be easy enough to do and far better than polar scopes which need to be aligned and iffy at best im my experance.

[Earl]

Well i may of sorted this.

Use cdc setup your ccd to show and zoom to pole

use http://www.lukepaynesoftware.com/projects/peek-through/ to make it transparent

Under it get your ccd softare frame and get the images to overlay.

make sure your ccd is level in the ota, make sure your home posision is accurate.

This must be better than using a polar scope?

[Earl]

CDC in the background to simulate sub

Stellaium over the top

getting them to match scales is the trick i think.

[Earl]

got the ccd boxes almost spot on

[peroni]

Could you use Astrotortilla for this?

Just a thought.

Apologies answering your question with another question. 

[Thalestris24]

Hi

An alternative is to use Astrotortilla PA tool to give you the PA error on a suitable target star. You can then use this little app, polefocus, http://www.scopefocus.info/polar-alignment to slew the amount of the error measured, then centre the target star using the alt/az adjusters. I've only tried this a couple of times and I can't guarantee it but it does seem to work. But it's only as good as the accuracy that AT gives for the PA error and AT can be temperamental... Also, it can be tricky to adjust in alt and az at the same time. Unfortunately I can't point to the meridian from where I am but if you can then using polefocus in conjunction with the Astrotortilla polar align tool might be quite good. It has the advantage of being independent of polaris.

You have to be careful about the values you input to polefocus and make sure you include a minus sign if necessary! If you put in wrong values it will slew to somewhere you didn't anticipate or want to go!!

Louise

[ronin]

Wouldn't the accuracy depend on the scope being equally accurately aligned with the RA axis of the scope?

Since you can polar alingn a mount but can also view sort of 360 degrees around you and up to 90 degrees above that would mean that the scope and mount are somewhat independant - you can point the scope anywhere. Otherwise all you would see is Polaris.

[peroni]

Another option is the get close with PA using the EQMOD polar alignment utility and then fine tune some more with the other tools.

[Earl]

Wouldn't the accuracy depend on the scope being equally accurately aligned with the RA axis of the scope?

Since you can polar alingn a mount but can also view sort of 360 degrees around you and up to 90 degrees above that would mean that the scope and mount are somewhat independant - you can point the scope anywhere. Otherwise all you would see is Polaris.

Im not sure about how accurate the Home posistion needs to be, aslong as the CCD is square to the earth done via a bubble for instance, I dont think it will matter, same with having the mount head level.

This is my latest test idea, its not quiet perfect though, getting the chart and ccd to align spot on is not easy.

[russellhq]

I've used the following techniques and it's served me well for 20min guides.

Firstly, aligning the polar scope with the mount. This is done in daytime and I used the following video to help me. It was pretty straight forward.

Secondly, I used EQMODs polar scope alignment tool, following this video. Again, it was fairly straight forward:

After doing both these things, my guiding seems to work fine all night.

Hope that is of some help!

[daz]

PHD2 has a drift align tool in it now, also - if this helps

[Dave_D]

I'm of the same opinion as russelhq. I've stopped using alignmaster and instead just use ascom alignment. It's worth taking a few hours to get the polarscope properly aligned and gives great alignment. I also found that it's much easier if i defocus polaris so it presents a disk to the reticle.