Installation of AstroImageJ on Mac OSX


This page is to help with installing the latest version of AstroImageJ on the Mac operating systems. The files linked from the server are complete and do not require a previous installation of ImageJ or AstroImageJ, or other software to run.

For more information, help from other users, and to post advice or questions please see the
AstroImageJ user forum on nabble

For the latest information on installing AIJ on Mac computers, see this post on the AIJ User Forum:
AstroImageJ installation instructions for Mac OS on AIJ User Forum

AIJ installation is currently not directly compatible with OS X 10.12, 10.13, 10.14, or 10.15+, but there is a new Java 8-based AIJ build that significantly simplifies AIJ installation. The new version only supports 64 bit Mac OS, so older Macs will need to continue to use the Java 6 installation.

Follow these steps to install the newer AIJ Java 8 version:

1) Download the latest AIJ Mac installation zip file that is labeled with "java8".

2) Double-click the installation file to decompress the app to "AstroImageJ".

3) Drag the AstroImageJ app to the Applications folder.

4) Open a terminal window and enter "xattr -d /Applications/" (without the quotes).

5) Double-click the AstroImageJ app and it should now open with no error messages.

6) Go to AIJ_Toolbar=>Edit=>Options=>"Memory and Threads" and update the "Maximum memory" value from the default 3000 MB to your preferred AIJ memory upper limit. It is recommended to set the value to ~75% of your computer's physical memory. For example, if you have 8 GB of memory, set the maximum memory value to 6000 MB.

7) Close and reopen AIJ to activate the new memory setting. Click on the bottom of the toolbar to verify that the new memory setting is retained, and verify that Java 1.8 is indicated. If so, you should be ready to use AIJ.

8) Use the AIJ Update feature at AIJ_Toolbar=>Help=>Update AstroImageJ to update to the latest numbered release or the daily build. The "Upgrade To:" box will default to the latest daily build version of AIJ. If you prefer the latest numbered release, select it in the dropdown box. Click "OK" and three files will be downloaded and installed in the proper location in the installation directory structure (you need write access to the installation directory). After the files have been installed, AIJ will automatically close. Restart AIJ to use the updated version.

Your AIJ installation should now be fully functional. STOP HERE.


If the older Java 6 version is required for installation, you will need to follow the more complex workaround steps described below.

There are currently two procedures that are tested to work with 10.14 and older, but jump to the separate section below for 10.15+ installation. The simplest only requires a command to be executed in a terminal window once the package is installed:

  1. Download the latest mac installation file.
  2. Unzip the installation file and move the AstroImageJ folder to the Applications folder
  3. Run this command in Terminal

xattr -r -d /Applications/AstroImageJ

That's it! AIJ should now start up normally. If it does, then follow the instructions below in the section labelled "Post Installation". There is no need to run both methods. We expect the first one will work for most users. If not, you could try this previous workaround that is a bit more complicated and requires superuser login.

  1. If you haven't already, Install AIJ by unzipping the install file and dragging the resulting AstroImageJ folder to the Applications folder.
  2. Open the Terminal app from the /Applications/Utilities/ folder and then enter the following command syntax: sudo spctl --master-disable
  3. Hit return and authenticate with an admin password.
  4. Relaunch System Preferences and go to the Security → Privacy → General tab.
  5. You will now see the Anywhere option under Allow apps downloaded from:. Select this option.
  6. Make a copy of /Applications/AstroImageJ/ on the desktop. An easy way to do that is hold down the alt key while dragging from the /Applications/AstroImageJ folder to the desktop.
  7. Delete the original copy of that is still in the /Applications/AstroImageJ folder.
  8. Drag the copy of from the desktop back to the /Applications/AstroImageJ folder.
  9. Start AIJ and set up your memory settings as needed.
  10. Close AIJ.
  11. After running AIJ the first time, enter the following command syntax to reenable GateKeeper (AIJ will continue to work normally): sudo spctl --master-enable

Installation for OS X 10.15+: Mac OS 10.15 and later requires additional installation workaround steps. Follow the detailed instructions outlined by Peter Plavchan at the link below.
AstroImageJ installation instructions for Mac OS 10.15 and later

In a couple of cases, it has been reported that the AIJ_Prefs.txt file can become corrupted as part of an upgrade to 10.15. This will cause various error messages/exceptions when starting sub-modules such as Data Processor (DP). If you are seeing those problems, then open Multi-Plot and navigate to File->"Restore all AIJ default preferences..." (at the bottom of the list) and follow the instructions in the AIJ messages provided to reset the defaults.

Post Installation: After installation you should change the upper limit on the amount of memory that is available to AstroImageJ and check for AstroImageJ updates. Both of these can be done at any time, and the updates will keep your installation current with bug fixes and new features.

On the Mac with this installation procedure AIJ can be started by double-clicking either the or the icons. Either app can be dragged to the Dock to provide convenient access for starting AIJ.