SX IO supports the locally installed astrometry.net tools to plate solve your images.
There’s currently no Mac installer for these tools that I’m aware of but they’re simple enough to install from the command line using homebrew. To do this you’ll have to use the Terminal app which you’ll find in /Applications/Utilities, a user account with administrator privileges and an internet connection.
You can simply copy and paste each one of the lines below into the Terminal window and press return after each one. Let each one run to completion before entering the next. Some will require that you enter your admin password.
Depending on the speed of your computer and internet connection each command should run fairly quickly. The last one which installs astrometry.net itself may take a bit longer.
The first time you run any of these commands you may see the following alert.
Press Install and allow it to complete. This will install the developer tools required to build astrometry.net and its dependencies.
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" brew install Caskroom/cask/xquartz sudo easy_install pip sudo pip install pyfits brew tap homebrew/science brew install astrometry-net
Now that the tools are installed you need to get some indexes for them to work with. The wide-field indexes are usually sufficient and only take up about 340MB of disk space as opposed to the full resolution ones which occupy 10GB.
To install the wide-field indexes type in the following commands. This creates a folder called astrometry.net-4100 in your Documents folder and downloads the index files to there.
mkdir -p ~/Documents/astrometry.net-4100 cd ~/Documents/astrometry.net-4100 curl -O http://broiler.astrometry.net/~dstn/4100/index-4[107-119].fits
Once they’re downloaded you can point SX IO to them using the file chooser in the Preferences… window.
That’s it, you should now be able to use the Tools-> Plate Solve command to solve your images.