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CARTA Sessions

CARTA is a browser-based tool for inspecting astronomical images and data cubes. Use it for interactive visualisation and region or spectral exploration; use a headless Session for a repeatable reduction.

Launch CARTA

  1. Sign in to the Science Portal.
  2. In Launch New Session, choose CARTA, select an image containing the software you need, and launch the Session.
  3. Wait for it to start under Active Sessions, then open its application link.

Save your work under /arc before using the Session's delete control in the portal. Closing the browser tab does not stop the Session. See Get started for account, storage, and cleanup steps.

Launch from the command line (optional)

Install the client before using these commands.

Choose an image published for the active server:

canfar login cadc
canfar image ls --kind carta
canfar create carta IMAGE_NAME --name cube-inspection

The Science Portal offers the same Session Kind. Available versions, resource controls, and supported file formats are deployment- and image-specific. Use the image description rather than assuming a version or startup time.

Monitor the Session and open it when ready:

canfar ps --all
canfar info SESSION_ID
canfar open SESSION_ID

For a Session that remains Pending, inspect events and resource troubleshooting.

Open data

CARTA can open files that the Session can read. Common workflows use FITS images or cubes under mounted Science Platform storage:

/arc/home/<user>/
/arc/projects/<project>/
/scratch/

For an object in a configured VOSpace Service, transfer it explicitly before opening it:

canfar data cp IDENTIFIER:/path/to/cube.fits local:/scratch/cube.fits

Use the Storage Identifier and path supplied by your project. /scratch is temporary; copy any regions, tables, or derived products that must survive to /arc or a persistent VOSpace Service. See Data transfers.

Interactive analysis

The exact controls depend on the CARTA version, but typical workflows are:

  1. open an image or cube from the Session filesystem;
  2. inspect WCS, channels, Stokes axes, and image statistics;
  3. draw regions and examine spectra or moment summaries; and
  4. export regions, tables, or figures to a persistent path.

Treat exported files as products of the analysis and record the input path, image version, and CARTA version with them.

Performance

Large cubes can require substantial memory, storage, and network traffic. Start with a representative sub-cube, close unused views, and stage a remote object to /scratch when repeated reads are required. Request only measured CPU or memory needs; fixed oversized requests may wait for matching capacity.

Troubleshooting

  • If the image is not listed, confirm the image with canfar image ls --kind carta and ask the deployment operator about availability.
  • If a file does not open, verify the path with canfar data info or stage a copy and check its format.
  • If the interface is slow, reduce the data subset and inspect Session resources before increasing the request.
  • If the browser disconnects, check canfar ps --all and canfar info before restarting the Session.

See Support for the diagnostic information to include when reporting a persistent problem.