Looking for beta testers of new Polar Alignment utility.

[themos]

Hello Andy, 

I rely on a whole bunch of python modules having been installed. That's why I suggested people use the Anaconda distribution, it includes everything I use. The miniconda distribution is another possibility but you'll have to manually install all the packages we need. In your case, it's the "ujson" module that is missing (we also need PIL, numpy, astropy, scipy). Your python is installed in C:\Python27. You may have a python module install-helper (perhaps "pip") already there, in which case you should try "pip install ujson" in a command window and similar commands for other missing modules.

[AndyKeogh]

Thanks for the quick response.  I have dumped my version of Python that Astrotortilla recommends and I have now successfully solved your test files.

All I need now are clear skies around Polaris.  May have to wait til Tuesday for that.

[themos]

I hope AstroTortilla still works!

[cthorpey]

Dumb Question Alert!

I am trying this with a canon1100d. Does the orientation of the camera with respect to the focuser make any difference?
Things were going quite well last night but I seem to be having some mechanical difficulties with the mount. The software was wotking and solving quite nicely.

Thanks

Chris
 

[AndyKeogh]

I hope AstroTortilla still works!

Well I have still to have a successful solve  but I do not get any  error messages.

2467 files appear to be the same except for the date stamp and there are an extra 33,769 files in the anaconda distribution.

Andy

[themos]

Dumb Question Alert!

I am trying this with a canon1100d. Does the orientation of the camera with respect to the focuser make any difference?

Things were going quite well last night but I seem to be having some mechanical difficulties with the mount. The software was wotking and solving quite nicely.

Thanks

Chris

Hello Chris, 

I realize I've been giving instructions thinking of the simple case of Camera + lens, where it is straightforward to tell if you are taking a landscape picture of the sky. If you're using a reflector, it's not that simple. The orientation of the camera in the focuser does not matter. All that matters is that the image that you select as "horizontal" is really horizontal, that is, the long side of the image corresponds to your horizon. I don't know how you'd do that with a Newtonian. Practice in the daytime, perhaps.

[cthorpey]

Thanks Themos,
I will test it out tomorrow as long as it doesnt rain.

If it does make a difference I will post some piccys to demonstrate.

Chris

[cthorpey]

Hi All,
have done some checking this morning and it seems that the orientation of the dslr to the focuser does make a difference on a newt!

I have now set the camera so that the base of the body is parallel to the tube / focuser knobs.

This means that when i move the scope 90 deg from vertical / home I will have the long edge at the bottom and hopefully should now get results that make sense. D'oh.

Chris.

Piccy is one i found on the net, not my setup.

[themos]

It makes a difference that can be countered by just swinging around the RA axis. I don't think there's a "correct" orientation of the camera in the focuser. But for repeatable operation, it would help to establish a baseline.

I would use the scope in the daytime, point it at the horizon, put the RA axis in "parking" state (weights down), and mark what orientation of the camera in the focuser will give you an image of the horizon that is, well, horizontal! 

[cthorpey]

yup, thats what I did. if I have my camera that way round I get the horizon horizontal.

[cthorpey]

YES!!!

Now that I have the camera oriented as described above the "move" instructions make sense and I now have a polar alignment error of 0.54 arc min.
I then started all over again, deleted my images and restarted PPA. I did the initial shots and checked alignment and it is exactly the same error.

Ooo I am a happy chappie. Going to celebrate with a nice hot chocolate then off to bed.

Themos, Thank You so much.
 

Chris

[themos]

Good news Chris, I'd like to collect some of those images so email me any time that's convenient. 

[AndyKeogh]

Thanks for the quick response.  I have dumped my version of Python that Astrotortilla recommends and I have now successfully solved your test files.

All I need now are clear skies around Polaris.  May have to wait til Tuesday for that.

What a great tool :)

My mount had been at the Galloway star camp  so I set it up from scratch yesterday.  Polar alignmnent took 3 iterations and was complete within 16 mins.

As a check for how good the alignment was I ran PHD unguided for about 82 minutes  and the PHDLab analysis is below.

As a comparison these images are of he output from PPA after completing alignmnet

Note the polar alignment error of 0.94 arc mins is quite close to the 0.83arc mins reported by PHDLab.

This is how it looked on hte alignment image

Improvement suggestion:-

1) Could you mark a cross in the image to show where NCP is  so that I can try to reduce hte error without reverting to drift alignment?

2) How difficult would it be to use Astrotortilla for hte plate solve?  At star camps I have been to there I have not had good enough internet access to support image transfer.

So thanks once again for a really useful tool.

Andy

[AndyKeogh]

I forgot to ask, how bad can polar alignment be before your app will not be able to sole it?

Andy

[themos]

Hello Andy, 

Thanks for the feedback, this is very useful.

1. I will add a green cross and more digits to the display of arcmin Moves

2. I have a newer version that can use local solves but it's tricky to make user-friendly. I'll see if I can "sniff" the AstroTortilla settings, if installed.

3. How bad can it be? I don't know, I should experiment! I can imagine it working even if the NCP region is out of the field of view.

Edited December 3, 2014 by themos

[D4N]

This is quite an interesting project, I'd be interested in testing it, do you have a OS X version of the installer?

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[themos]

Hello D4N, I don't. Do you have Anaconda on your machine? I can package up the files in a .zip container for you.

[D4N]

Yep I have Python installed.

If you can provide the files I'll give it a whirl and see what happens.

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[cthorpey]

Themos, will do.

Just a note to anybody using APT with this, I was able to reduce file upload times and solve times by reducing the image quality in APT to "M".

Local solving would be a great bonus but I am more than happy with the way it works.

Chris
 

[themos]

Oh yes, you don't want > 1MB files being uploaded, stick to the lowest resolutions. 

[themos]

Hello

Here is Version 1.0.3 with the ability to use a local astrometry.net solve. 

When you first run it, the Local buttons should be disabled. You need to go to AstroTortilla and create two new configurations, called PPA_coarse.cfg and PPA_fine.cfg. You can just copy the one configuration that works for you to both these names (I use AT's File -> Load Settings... and File -> Save Settings...). If those files are present, PPA will, on restart, have the Local buttons enabled.

Personally, I created two "Backend config" files for astrometry.net's solve-field command: one with just the 4100-series indices that is good for widefield images and a second one  with just the 4200-series indices. The first time you do a local solve in PPA, the PPA_coarse is used, in subsequent solves the PPA_fine is used. We only copy these AT settings:

Backend config, Downscaling, Scale minimum, Scale maximum, Scale units, Cygwin shell, Custom options.

In future, depending on feedback, we may only steal settings from one AT settings file. 

[cthorpey]

Themos,

It would appear that my "neat freak" tendencies took over and I have deleted the images I took when aligning. 
As soon as I get another clear night I will re do it for you and send the images. Sorry.

is it just the images you need?

Chris

[astromerlin]

I've just stumbled onto this very interesting project, now for the dumb question, will the accuracy of polar alignment using your method be affected if I have cone error in my setup?

[themos]

Themos,

It would appear that my "neat freak" tendencies took over and I have deleted the images I took when aligning. 

As soon as I get another clear night I will re do it for you and send the images. Sorry.

is it just the images you need?

Chris

Ok, just the images, yes. Thanks!

[themos]

I've just stumbled onto this very interesting project, now for the dumb question, will the accuracy of polar alignment using your method be affected if I have cone error in my setup?

It shouldn't be affected but we'll have to see what happens in practice. If your image scale is quite fine, there may be issues. It's been tested quite a bit with image scales of 5 arcsec/pixel and above.