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Hubble Space Telescope
Windows: How to Download, Install, and Start APT

Supported Systems

APT is supported on Vista, Windows 7 SP1+, 8 and 10.

APT requires a minimum of 512 Megabytes of RAM (memory), but we recommend at least 1 Gigabyte of RAM. Please see our memory discussion for more information.

APT is only available as a 64-bit version for Windows. (To determine which you have look at the System information in the Control Panel.)

Depending on your institution's computer security measures (firewalls, blocked ports, etc.), you may initially have communication trouble with APT (looking up an Investigator for instance). If you have any concerns please see our firewall webpage.

1. UnInstall the previous version

If you are going to install APT in the same folder as a previous version, please remove the previous version first. If you are going to install in a separate folder, you still might consider uninstalling to save disk space (and possible confusion between the different versions).

Here are instructions for getting rid of the old APT:

2. Download and Install

Install APT to a folder you have default privileges for: We recommend installing this software into the default location (which is a folder within the user's home folder). In situations where APT must be installed into a common area (such as C:\Program Files), you may need to use an actual Administrator account and not an account that has Administrator privileges or some institution-specific configuration of heightened privileges. If you choose to install to this location, please be sure to specify a folder within Program Files e.g. C:\Program Files\APT_27.1.

Proceed to the Installation...

3. Start

Once you have installed APT you can invoke it from the Start menu if you have created shortcuts. For instance if you chose the default shortcuts, go to Start menu and choose Programs>STScI>APT_27.1>APT. If you did not create shortcuts, you may invoke APT from the APT installation folder.

4. Help

There is a series of short training movies which will help get you started (there are also web pages with screen shots available on the same page). APT also has documentation available from the "Help" menu (the right-most menu on the menu bar).

If you can't find what you need, please contact us at

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


If there are problems with the installation you can turn on debug logging and sometimes that will reveal the problem. 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 during installation:

To turn debug logging on while running APT: Go to the APT installation folder and double click on the APT.bat icon.

Known Installation/Download Problems: