AstroTortilla issue

[zicklurky]

Hiya,

I'm hoping someone can help, I'm pulling my hair out! I just can't seem to get AT to solve this image. Astrometry.net solves it super quickly. 

I've attached the image, and the Astrometry.net link is http://nova.astrometry.net/user_images/388001#annotated

My custom options are: --sigma 70 --no-plots -N none -r --objs 100, with my degwidth between 2.8 and 3.75.

Most of my other images solve is under 30 seconds, but this one takes forever, and then doesn't solve.

Help!!

[Stargazer33]

Have you installed the index files that correspond to the fov in your image?

[Skipper Billy]

2.8 - 3.75 sounds like a narrow band. You don't state what rig you are using but whatever it is I think the recommended max is 1.5 times your max field of view and half the minimum field of view. You may be excluding the very plates it needs to solve the image ???

[zicklurky]

Hmmmm I increased --objs to 200 and it finally solved, but took 20 minutes.

My fov is 3.68 by 2.94 degrees, so I input the fov very close to this to speed up solving.

[zicklurky]

Success! I upped the downscaling to 4, and removed all but 2 of the index files, and now it's solving very speedily. Hooray!

[Gib007]

What I do when I'm intending on imaging in narrowband with a refractor, say in Hydrogen-Alpha, is I focus with the Hydrogen-Alpha filter but then before getting AstroTortilla to do its job, I switch to the filter which is closest (Red). Since it's a broadband filter, AstroTortilla has a much easier time of picking up many stars to use in plate solving. Once done, I switch back to Hydrogen-Alpha and image away. If using Oxygen-III, I tend to switch to Green for AstroTortilla. For Sulphur-II, obviously Red also works well. 

I do agree that though you may wish to set AstroTortilla to have FOV limits 50% above and 50% below your own limits, the more constrained the limits are (minimum, your own FOV limits, of course), the faster plate solving goes.