Mac OSX: How to Download, Install, and Start APT

Supported Systems

Hardware: Apple has recently released new Mac hardware based on Apple Silicon (M1). We have discovered that the HST Orbit Planner and Visit Planner tools are not compatible with this new hardware. (The JWST Visit Planner is not affected.) An upgrade is being investigated.

Operating System: APT requires Mac OSX 10.10 (Yosemite) or higher.

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 Mac OS X, 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 installer below then double-click APT.pkg to start the installation.

Download the 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 is in Applications/APT_2020.2.1/) 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.