Hi Andrew, Robert,

as I might be the reason for that not home-brew python3 install, just to try to help in this area. OS X might also go away from python 2.7 in future as they stated, that they don't like to support other frameworks than their own from a fresh install. Things might get more complicated, because if you have an "old" system running (with python2.7 installed) and update to a newer OS X release, the python might be still there, but for a brand new computer, it won't be installed from scratch on.
As I did some work with astrometry.net on three different platforms (mac, win, linux) things improved, when staying with the official python.org installer. For the software I'm developing (MountWizzard), the situation lead for astrometry.net to call the executables from the python program directly. You only need two binaries for doing plate solving. All other stuff could be omitted. In result you don't need any python, if you arrange the two tasks: star extraction (from fits to *.xy file) and solving (from *.xy file to coordinates). Yes you might loose some parameters to set, but I found this not really restrictive for users. If you would like to experience this way, please let me know. I try to explain how I did this. As result I don't care even on OS X about the python versions installed as I don't need them.

Another solution is ASTAP (OK, it's not astrometry.net, and it does right now not calculate distortion parameters), but installation on multiple platforms is easy.

Michel

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