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CARTA is the Cube Analysis and Rendering Tool for Astronomy, a new image visualization and analysis tool designed for the ALMA, the VLA, and the SKA pathfinders. As image sizes continue to increase with modern telescopes, viewing an image with a local image viewer or with a remote image viewer via the ssh protocol becomes less efficient. The mission of CARTA is to provide usability and scalability for the future by utilizing modern web technologies and computing parallelization.

Download and Installation (see

CARTA is a separate application and not directly integrated with CASA. Refer to the official CARTA website for download and installation instructions as well as a proper set of documentation.

Some advantages over the CASA Viewer (tasks imview and msview):

  • Much better performance, able to handle very large image cubes

  • Modern web browser based interface allowing local and remote display options.

  • Can display Stokes wedges.

  • Proper display of image headers

  • Flexibility to modify and save the layout

  • Supports new HDF5 image format (in addition to CASA Image, MIRIAD, and FITS)

  • Rotation support for regions

  • RMS display for spectra

  • Better image rendering widget

  • Better animation control

  • Gzip image display

Subsequent releases of CARTA will continue to enhance CARTA’s performance. For a full overview of the current and upcoming features, see the official CARTA website.


CARTA is developed by the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), the Inter-University Institute for Data Intensive Astronomy (IDIA), the National Radio Astronomy Observatory (NRAO), and the Department of Physics, University of Alberta.

Remaining Capability Gaps

Note: CARTA does not yet offer an exact replacement for every feature in the old CASA Viewer (tasks imview and msview). Many things are complete, and CARTA offers a good deal of enhanced functionality over the imview task, but a small subset of things may still be missing.

Some remaining features of the CASA Viewer that are not yet in CARTA:

  • Position-velocity map generator

  • Complete set of fitting tools

  • Source finder tool

  • Tabular axis support

  • Spectral profile error bar plotting

  • Partial image cube loading

  • Image and profile annotation

  • Rotated cube view (input as ra-dec-channel, view as ra-channel vs dec)

  • Scalable output (SVG or PDF)

  • Creation of multi-channel plots

  • Ability to reapply rest frequency for velocity conversion

  • Regions that extend across spectral and stokes planes

  • Histogram fitting

  • Complex Image support

  • Multi-panel display (available in v3-beta1)

  • Distance measuring tool (available in v3-beta1)

Interactive Clean

The CASA Viewer serves as both a stand-alone analysis platform for image artifacts, as well as an interactive front-end to control CASA execution (via interactive clean).

CARTA is focused on providing image analysis to a wide variety of groups and organizations, some of which are not affiliated with CASA or only have access to the output images. Integrating CASA and CARTA together through interactive clean control would not be efficient.

Instead, the CASA team is developing a separate interactive control interface for users of CASA. This interface will include interactive clean unified with other widgets in the CASA suite related to runtime execution, status, and control. This interface will not duplicate CARTA analysis functionality and is intended to be used in conjunction with CARTA for image viewing. More details will be provided as development progresses.

MS View

The CASA Viewer is also able to open MeasurementSet format files for raster display and flagging of visibility data. CARTA will focus solely on image format files (including FITS and HDF5). The CASA team is working to migrate MS view and PlotMS to a new unified MeasurementSet plotting and analysis utility. More details will be provided as development progresses.

Using CARTA with CASA

The CARTA Website provides download links for CARTA on a variety of platforms and usage types. CARTA is intended for more than just CASA usage and supports installation within large data warehouses and archives.

Refer to the CARTA installation and configuration instructions for more information.

Personal laptops or workstations

Many users expect to run CARTA alongside a CASA instance to view the products produced by CASA. The Stand-alone application version of CARTA is intended for this purpose.

If you are running CASA on your own laptop or workstation that you are directly using (so the machine where the data reside is the same that will render the visualization), then simply downloading and executing the Stand-alone application version of CARTA for your OS is sufficient.


If you are running CASA or viewing data products on a cluster, you should have a site deployment of CARTA configured by your system administrator. This is a single CARTA instance that is always running at a fixed URL and allows users to connect with their institution login credentials.

Note that the stand-alone application version of CARTA may work on a cluster through ssh/VNC with the --no_browser option discussed in the next section, but the site deployment version is the intended distribution for this type of usage.

Running CARTA at NRAO

Instructions for users within the NRAO network or staff with external VPN access

Warning: The default Firefox installation on some NRAO machines may not support the WebGL version of CARTA. Try Chrome or contact the helpdesk for an updated version of Firefox

Using the Site Deployment version

NRAO has set up a provisional site deployment of CARTA for users running CASA on the CV cluster. This is a temporary instance on borrowed hardware intended to allow for initial access while permentant hardware is procured.

  • Before starting: in your linux home directory, create symbolic links to the directories on /lustre that have the data that you wish to visualize

  • If you are outside the NRAO network, you must start a VPN connection to NRAO (e.g.

  • login with your NRAO userid/password

Note: This provisional server is in CV and can only access CV lustre filesystems. There is no NM-based CARTA server at this time

Remotely Connecting to a NRAO Workstation or Cluster

If the site deployment version is not an option for you, then you can instead invoke the stand-alone installation of carta by using the --no_browser switch:

  1. Connect your home computer to the NRAO VPN

  2. (Optional) Reserve a cluster node in the usual manner

  3. $ ssh <username>@your_cluster_node or $ ssh <username>@your_workstation from your home computer, or from a terminal in a remote VNC or fastx desktop display

  4. from the ssh or VNC/fastx terminal, (optional) cd to the directory where the data you want to visualize live and (not optional) type one of the following:

    • $ carta --no_browser

    • $ APPIMAGE_EXTRACT_AND_RUN=1 carta --no_browser

    This starts the CARTA backend on the remote machine and prints a link to the terminal

  5. Copy the link printed to the screen to a web browser opened on your home computer (not a web browser within your VNC or fastx display).

NOTE: Using the CARTA stand-alone application version through VNC or fastx without the –no_browser option may not work or will lead to significantly diminished performance (since it bypasses CARTA’s graphics acceleration features). While this is how one would typical use the CASA viewer or DS9, this is not how CARTA is designed to be used.