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macOS: How to Download, Install, and Start APT

Supported Systems

Hardware: Apple Silicon chips (M1/M2/M3) were previously causing the HST Orbit and Visit Planners to run much more slowly. An Apple Silicon native version of the language APT uses for the HST Orbit and Visit Planners is now available. So there are now two installer packages for macOS: one for Intel chips and one for Apple Silicon chips. (Note that despite running on Silicon chips, devices running iOS - such as tablets - cannot run APT.)

Operating System: Beginning with APT 2023.5.1, APT requires macOS 10.12 (Sierra) or higher for Intel chips and macOS 11 (Big Sur) or higher for Apple Silicon chips. Please note that APT may or may not work on operating systems that are past their "end-of-life" (and it may be difficult to trouble shoot unfamiliar issues).

Important exception: The HST Orbit Planner and Visit Planners now require macOS 12 (Monterey) or higher. We are investigating possible workarounds, but since macOS 10 and 11 are at "end-of-life" (no longer supported by Apple with upgrades) we encourage you to upgrade your operating system.  Please contact us (through if this is an issue for you.

Depending on your institution's computer security measures (firewalls, blocked ports, etc.), you may initially have communication trouble with APT. If you have any concerns please see our Server Connectivity knowledge article.

NOTE: APT is delivered as a native installer package on macOS, so the download is named "APT_*.pkg".


1. Uninstall the previous version

Note: If you are going to install APT in the same folder as a previous version, please remove the previous version first. But if you are going to install in a separate folder, you would only need to uninstall to save disk space (and possible version confusion).

To get rid of the old version: delete the entire folder where you installed it.


2. Download and install

Download the appropriate installer below then double-click APT_*.pkg to start the installation.

(If you have trouble installing APT, please see the Troubleshooting Tips at the bottom of these platform specific Installation instructions.)

Download the macOS Intel Installer

Download the macOS Apple Silicon Installer

View the SHA Number


3. Start

Once you have installed APT you invoke it by clicking on it. Go to the installation folder (default installation folder has a name like Applications/APT_202x.x/) and double click on APT.


4. How to find out about new releases

We maintain a distribution list for announcing new releases of APT. This may be helpful to people who install APT for others to use. Just send a blank email to: (Unsubscribe by sending a blank email to


5. Troubleshooting

If there are problems with the installation you can turn on debug logging and sometimes that will reveal the problem. (For instance, one user found that there was a permissions problem and all that was needed was to run "Repair Disk Permissions"). This debug log would also be useful to send us if you can't figure out the problem. Contact us (through if you have problems with installation.

To turn debug logging on while running APT:

  • Go to the folder where you installed APT.
  • Double click on the apt script in the bin folder.

Known Installation/Download Problems:

  • None at this time. Please contact us (through if you have problems with installation.