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Launching CARTA Sessions

CARTA (Cube Analysis and Rendering Tool for Astronomy) is a specialized image visualization and analysis tool designed for radio astronomy data. This guide walks you through launching and using CARTA sessions on the CANFAR Science Platform.

🎯 What You'll Learn

  • How to launch a CARTA session and choose the right version
  • How to size RAM/CPU for your datasets
  • How to load data from /arc and work with radio data cubes
  • Tips for analysis features, performance, and troubleshooting

Overview

CARTA provides advanced features for:

  • Image visualization: Multi-dimensional data cube exploration
  • Spectral analysis: Line profiles and moment maps
  • Region analysis: Statistical analysis of image regions
  • Animation: Time-series and frequency animations
  • Collaboration: Real-time session sharing

Creating a CARTA Session

Step 1: Select Session Type

From the Science Portal dashboard, click the plus sign (+) to create a new session, then select carta as your session type.

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Step 2: Choose Container Version

Note that the menu options update automatically after your session type selection. Choose the CARTA version that meets your needs:

  • CARTA 4.0 (recommended): Latest features and bug fixes (The screenshot is old and showed older versions only.)

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Step 3: Configure Session

Session Name

Give your session a descriptive name that will help you identify it later (e.g., "m87-analysis", "ngc-1300-cube").

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Memory Configuration

Select the maximum amount of RAM for your analysis. Choose the smallest value reasonable for your needs, as resources are shared among all users:

  • 8GB: Small images and simple analysis
  • 16GB (default): Most radio astronomy datasets
  • 32GB+: Large data cubes or complex multi-image analysis

Choosing Resources

Start with 8GB RAM and 2 CPU cores. Increase memory for very large FITS or CASA images and increase cores for CPU-intensive operations like moment map generation.

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CPU Cores

Select the number of computing cores. CARTA can benefit from multiple cores for certain operations:

  • 1 core: Basic image viewing
  • 2 cores (default): Recommended for most tasks
  • 4+ cores: Large data processing and animations

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Step 4: Launch Session

Click the Launch button and wait for your session to initialize.

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Your session will appear on the Science Portal dashboard with your chosen name. Click the CARTA icon to access your session.

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Using CARTA

Initial Setup

Wait for CARTA to load completely. You'll see the main CARTA interface:

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Loading Data

  1. Click the folder icon in the upper left to navigate directories
  2. Browse to your data location:
  3. Project data: /arc/projects/[group]/
  4. Personal data: /arc/home/[username]/

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Load an Image

  1. Navigate through the directory structure to find your FITS file
  2. Select the file you want to visualize
  3. Click the Load button

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Basic Operations

Image Display

Once loaded, your image appears in the main viewer with:

  • Zoom controls: Mouse wheel or toolbar buttons
  • Pan: Click and drag to move around the image
  • Colormap: Adjust scaling and color scheme

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Data Cube Navigation

For 3D data cubes:

  • Channel slider: Navigate through frequency/velocity channels
  • Animation controls: Play through channels automatically
  • Spectral profile: Click on pixels to see spectral information

Region Analysis

Create analysis regions:

  1. Select region tools from the toolbar
  2. Draw regions on your image
  3. View statistics in the statistics panel
  4. Export region data if needed

Advanced Features

Moment Maps

Create moment maps from data cubes:

  1. Load your data cube
  2. Go to File → Generate Moment Map
  3. Select moment type (0, 1, or 2)
  4. Set channel range
  5. Generate and display

Spectral Line Analysis

Analyze spectral profiles:

  1. Click on any pixel to see the spectrum
  2. Use the spectral profiler for detailed analysis
  3. Fit Gaussian profiles to lines
  4. Measure line properties

Contour Overlays

Add contour overlays:

  1. Load a second image
  2. Go to View → Contours
  3. Adjust contour levels and styling
  4. Overlay on your main image

Session Sharing

Real-time Collaboration

Share your CARTA session with collaborators:

  1. Click the session menu
  2. Select "Share Session"
  3. Add collaborator usernames
  4. Set permissions (view-only or full control)

Export and Save

Save your work:

  • Export images: File → Export Image (PNG, JPEG, PDF)
  • Save regions: File → Export Regions (DS9, CRTF formats)
  • Save session: File → Save Layout (restore later)

Data Format Support

CARTA supports multiple astronomical image formats:

  • FITS: Standard astronomical format
  • CASA images: Radio astronomy standard
  • HDF5: Large dataset format
  • MIRIAD: Legacy radio format

Performance Tips

Optimization

  • Close unused images: Reduces memory usage
  • Use appropriate data types: Float32 vs Float64
  • Enable GPU acceleration: For supported operations
  • Adjust cache settings: Balance memory vs speed

Large Data Cubes

Very large cubes can consume significant memory. Load subregions, work with decimated data, or increase RAM to avoid crashes.

Large Dataset Handling

For very large files:

  • Use decimation: View subsampled versions first
  • Load subregions: Focus on areas of interest
  • Consider preprocessing: Use CASA to create smaller working files

Troubleshooting

Common Issues

CARTA won't load - Check browser compatibility (Chrome/Firefox recommended) - Disable browser extensions that might interfere - Clear browser cache and cookies

Performance problems - Reduce image size or resolution - Close other applications - Check available memory

File loading errors - Verify file format compatibility - Check file permissions in storage - Ensure file isn't corrupted

Display issues - Try different colormaps - Adjust image scaling - Check graphics driver compatibility

Getting Help

Best Practices

Workflow Organization

  • Organize data: Keep raw and processed data separate
  • Document analysis: Save session layouts for reproducibility
  • Version control: Track analysis parameters and results

Resource Management

  • Monitor usage: Check memory consumption during analysis
  • Clean up: Close sessions when finished
  • Share efficiently: Use view-only sharing when appropriate

Next Steps