You can use the script ImageSolver to try to find the the parameters for solving one of your images. When you have these parameters then you can use them in AperturePhotometry.
ImageSolver has a manual that explains all the parameters and it gives some tips for configuring the script. You can read it clicking the documentation button in the script or at http://pixinsight.com/doc/scripts/ImageSolver/ImageSolver.html
Andrés.
Thx Andrés for your answer, i tried to use ImageSolver before use APS to be honest, i would like to do a HRD, i saw a post about it on the forum and i would like to try the technic of APS. In fact, i would like to take the picture of Omega Centauri of Hubble to try my first HRD. But i tried all catalog, anyway, it doesn't work...
I tried to find the caracteristic of this picture, but it founds stars but no match with PPMXL catalog...
I m not sure of the resolution of the picture but is there a mean to help ImageSolver to find match stars, i mean maybe an universal value
![Wink ;)](http://pixinsight.com/forum/Smileys/default/wink.gif)
When we don't have access to all settings of the camera of Hubble telescop.
Best Regards
PS: Technical settings of the picture :
http://hubblesite.org/newscenter/archive/releases/2009/25/image/q/