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Installing the Observing Tool

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Version of the Gemini Observing Tool was released on March 2, 2020 to support 2020A Phase II preparation.

The OT keychain is normally preserved between versions (starting in 2015A), however the 2016B OT is incompatible with previous keychains, so you will need to re-enter your keys if upgrading from a pre-2016B version.

New features are described in the Release Notes.

The remainder of this page contains instructions for downloading and installing the Gemini Observing Tool (OT). You can install the software on a network of workstations or, for best performance, on individual machines. This machine needs internet access to communicate with databases situated at the Gemini Observatory and with other on-line image and catalog servers. Anyone installing an OT for a multi-user environment should read the site-manager details

If you experience any problems installing or running the OT, please see the Frequently Asked Questions (FAQ) or known bugs pages for the latest information.

If you are installing the OT for the first time, please read the installation instructions. The OT installation files are located on the Gemini software site.

cautionPre-Upgrade Instructions

The OT stores programs in a local database in each user's home directory. The format of the binary files in this database is specific to each OT version and so they must be converted each time the OT is updated. Before installing a new OT, make sure to sync all local changes with the ODBs. If there are local programs in your database that you would like to save or to transfer to a new OT version, then export them to XML files (see the saving and loading help page for more details) for backup and reference. The "Bulk Export to a Selected Directory" option is useful for saving a bulk selection.  Old programs may be imported into the new OT as needed from the XML backups, or keep the previous OT version. We recommend that you download programs afresh from the ODB rather than import them from XML.

Additional Information

It is possible to have more than one version of the OT installed, although this can lead to a higher chance of confusion and problems. Each version of the OT will have its own, independent, local database.  Installing a new OT will not remove the database from the previous version. If you did not export your programs to XML and a new OT suddenly shows that you have nothing in your database, DON'T PANIC! As long as the ~/.ocs15/* directories are not deleted then the previous database still exists, and you just need to use the earlier version of the OT to access them, and if needed, export the programs to version-independent XML files.

The auto-update feature is not yet available, so it must be installed from the distribution files.

Installing the Observing Tool

Distribution files for the following operating systems are available:

  • macOS (10.3.3, Mountain Lion, or newer)
  • Linux (RHEL/CentOS or Fedora recommended, although likely compatible with other distributions as well)
  • Windows (Vista/ 7/ 8/ 10)

The OT software is available on the Gemini software site. This is an HTTP server so you should use your web browser to download the files. Depending on your browser, right or shift+click to save the file. Alternatively you may request a CD-ROM containing versions for all operating systems by e-mailing Bryan Miller (

Using and Installing the OT on macOS

The OT can be used on macOS 10.8.3 and newer releases (Mountain Lion, Mavericks, Yosemite, El Capitan, Sierra, High Sierra, Mojave, and Catalina).


  • Download the current macOS distribution of the OT from the Gemini software site by clicking the file named ot__macos.dmg ( download).
  • The macOS release is provided as a mountable disk image. Simply double click on the disk image to mount it, then drag the Observing Tool icon to the Applications folder, your DeskTop, to the Dock or to any place you find convenient. Double click on the icon to launch the application.

On recent versions of macOS, especially 10.15 (Catalina), you will need to give the application permission to run the first time that you use it. You can either:

  • Ctrl-click the application icon, select Open and then click Open in the subsequent dialog
  • Double-click the app icon, then click Ok in the subsequent dialog. Then open System Preferences -> Security & Privacy -> General and click on Open Anyway. Finally, click Open in the next dialog.

We are working on having the OT application signed by Apple so that this will no longer be required.

For OT benchmarks please see the PIT installation page for somewhat related Java benchmarks.

Using and Installing the OT on Linux

The OT can be used on most recent 32- and 64-bit Linux distributions. It has been extensively tested under RHEL/CentOS 5, 6, and 7, and Fedora up to release 30. We have not heard of any problems on other Linux distributions.


  • Download the current Linux distribution of the OT from the Gemini software site by right or shift+clicking the file named ot__linux64.tar.gz (64-bit) or ot__linux32.tar.gz (32-bit) ( download).
  • Unpack the distribution: tar -xvfz FILENAME.tar.gz
  • The distribution unpacks into a single directory named "ot__linux32" or "ot__linux64".
  • Make sure that the libgnome libraries are installed. These are needed to display file attachments. These can be installed with the following commands:
    Ubuntu/Debian: sudo apt-get install libgnome2-bin
    RedHat-based: sudo yum install libgnome
  • Run the OT. You can use the complete path to the startup script, as shown below (where the $ represents your shell prompt), or you can include that directory in your PATH.
    ${where_you_untarred}/ot__linux(32 or 64)/ot_

Results from previous benchmarking of the OT are shown below. Sufficient memory appears to be the most important element affecting performance and, whilst OT may run with less, we suggest a minimum of 2GB of memory and a Core 2 Duo or newer processor when using the Observing Tool.

Using and Installing the OT on Windows

The OT can be used on Windows Vista, 7, 8, 10, and Server 2008/2012. It has been tested on Windows 7 and 10, and we have no reason to believe there will be problems in other Windows versions as long as the Java included in our distribution is used.

You may encounter a font display problem in Windows 10 due to an issue with Windows/java font scaling. This does not affect functionality. A workaround is to change the scaling of text and apps to between 100% and 175%, depending on screen resolution.


  • Download the current Windows distribution of the OT from the Gemini software site by right or shift+clicking the file named ot__windows.exe ( download).
  • The Windows distribution is provided as a Windows executable installer.
  • Use Windows Explorer to display the directory in which you downloaded the installer.
  • Double-click the installer executable. When the installation is completed, select "Close" to exit the installer.
  • The installation places a "Gemini\Observing Tool\Gemini OT " folder in your Start menu. Double-clicking Observing Tool from this menu launches the OT.

Results from previous benchmarking of the OT are shown below. Sufficient memory appears to be the most important element affecting performance and, whilst OT will run with less, we suggest a minimum of 2GB of memory and a Core 2 Duo or newer processor when using the OT on the Windows platform.

Gemini Observatory Participants