CARTA Sessions

CARTA (Cube Analysis and Rendering Tool for Astronomy) for astronomy data visualisation

🎯 What You'll Learn

• How to launch CARTA sessions and choose the right version
• Loading data from CANFAR storage and working with radio data cubes
• Key features for spectral analysis, region analysis, and animations
• Performance tips and troubleshooting guidance

CARTA is a specialised image visualisation and analysis tool designed specifically for radio astronomy data. It excels at handling multi-dimensional data cubes, providing powerful tools for spectral analysis, and enabling real-time collaborative workflows.

📋 Overview

CARTA provides specialised capabilities for:

Key Features

Feature	Capability
Image Visualisation	Multi-dimensional data cube exploration with WCS support
Spectral Analysis	Line profiles, moment maps, and velocity analysis
Region Analysis	Statistical analysis of user-defined image regions
Animation	Time-series and frequency animations through data cubes
Collaboration	Real-time session sharing with multiple users
Performance	Optimised rendering for large astronomical datasets

Data Format Support

• FITS files: Standard astronomical format with full WCS support
• HDF5 files: High-performance format for large datasets
• CASA images: Native support for CASA image formats
• Compressed formats: Automatic handling of gzipped files

🚀 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.

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:

Available Versions

• CARTA 4.0 (recommended): Latest features and bug fixes
• CARTA 3.x: Previous stable releases for compatibility

Version Selection

Use the latest version (4.0+) unless you specifically need compatibility with older workflows. New versions include performance improvements and additional features.

Step 3: Configure Session

Session Name

Choose a descriptive session name to help you identify it later:

Good session names: - m87-analysis - ngc-1300-cube - alma-co-line-study - vla-continuum-imaging

Resource Allocation

Start with a "flexible" session for most analyses. Switch to a fixed resource allocation if you need guaranteed performance for demanding visualisations.

Resource Guidelines: - Flexible: Good for most CARTA workflows - Fixed: Use for large datasets (>1GB) or guaranteed performance

Step 4: Launch Session

Click the Launch button and wait for your session to initialise. CARTA sessions typically start within 30-60 seconds.

🧭 Using CARTA

First Steps

Once connected to your CARTA session:

1. File Menu: Use "Open Image" to load your data
2. File Browser: Navigate to /arc/projects/[project]/ or /arc/home/[user]/
3. Load Data: Select FITS or HDF5 files to visualise

Data Loading

From CANFAR Storage

# CARTA can access files from:
/arc/home/[user]/                    # Your personal data
/arc/projects/[project]/             # Shared project data
/scratch/                            # Temporary high-speed storage

Supported File Paths

• Local files: Any file accessible in the session filesystem
• Remote files: HTTP/HTTPS URLs (limited support)
• Archive data: Files downloaded to CANFAR storage

Interface Overview

Main Components

• Image Viewer: Central panel showing the astronomical image
• File Browser: Left panel for navigating and opening files
• Region List: Panel for managing analysis regions
• Statistics: Real-time statistics for selected regions
• Spectral Profiler: Panel for line profile analysis
• Animation: Controls for cycling through cube slices

Essential Controls

Control	Function
Mouse wheel	Zoom in/out
Click + drag	Pan around image
Right-click	Context menu with additional options
Keyboard shortcuts	See Help menu for complete list

🔬 Analysis Features

Spectral Analysis

Line Profiles

1. Draw regions on the image
2. Open Spectral Profiler panel
3. Select region to view spectrum
4. Analyse lines with built-in fitting tools

Moment Maps

CARTA can generate:

• Moment 0: Integrated intensity
• Moment 1: Velocity field
• Moment 2: Velocity dispersion

Region Analysis

Creating Regions

1. Select region tool from toolbar
2. Draw on image: Rectangle, ellipse, polygon, or point
3. View statistics in the Statistics panel
4. Export regions in DS9 or CRTF format

Statistical Analysis

CARTA automatically computes: - Sum, mean, RMS within regions - Min/max values and positions - Flux measurements with proper units - Histogram analysis of pixel values

Animation and Navigation

Data Cube Navigation

• Slider controls: Navigate through spectral channels or Stokes parameters
• Animation playback: Automatic cycling through cube slices
• Frame rate control: Adjust animation speed
• Custom ranges: Focus on specific velocity ranges

Multi-Panel Views

• Compare datasets: Load multiple images simultaneously
• Linked panels: Synchronise zoom, pan, and navigation
• Layout control: Arrange panels as needed

⚡ Performance Optimisation

Large Dataset Handling

Memory Management

# Monitor session resources
htop                    # Check memory usage
df -h                   # Check disk space

Optimisation Tips

• Use /scratch for large files: Copy data to high-speed storage
• Close unused files: Reduce memory consumption
• Reduce image resolution: For initial exploration
• Use data subsets: Work with spatial/spectral sub-cubes

Network Performance

For Remote Access

• Stable connection: CARTA requires consistent network connectivity
• Bandwidth: Higher bandwidth improves responsiveness
• Close other applications: Reduce network competition

🤝 Collaboration Features

Real-Time Sharing

CARTA supports collaborative analysis:

1. Share session URL with team members
2. Simultaneous access: Multiple users can connect
3. Synchronised views: All users see the same state
4. Coordinate activities: Communicate to avoid conflicts

Best Practices for Collaboration

• Designate a lead: Have one person control navigation
• Use voice/chat: Coordinate complex operations
• Save work frequently: Export regions and analysis results
• Plan sessions: Organise collaborative time in advance

🔧 Advanced Features

Scripting and Automation

Export Capabilities

• Image exports: PNG, JPEG, PDF formats
• Region files: DS9 or CRTF format for other tools
• Spectral data: CSV format for further analysis
• Session state: Save and restore CARTA configurations

Integration with Other Tools

# Load CARTA regions in Python
from astropy.io import fits
from regions import Regions

# Read CARTA-exported region file
regions = Regions.read('carta_regions.crtf', format='crtf')

# Use with other astronomy software

Custom Colour Maps

• Built-in maps: Scientific colour schemes
• Custom maps: Import your own colour tables
• Accessibility: Colour-blind friendly options
• Publication quality: High-contrast options for papers

🔧 Troubleshooting

Common Issues

Session Won't Load Data

Problem: CARTA cannot open FITS files

Solutions:

1. Check file permissions and location
2. Verify file format is supported
3. Try copying file to /scratch/ first
4. Check file isn't corrupted

Slow Performance

Problem: CARTA responds slowly to interactions

Solutions:

1. Check available memory with htop
2. Close other browser tabs/applications
3. Reduce image size or use sub-cubes
4. Restart session if memory is exhausted

Connection Issues

Problem: Lost connection to CARTA session

Solutions:

1. Refresh browser page
2. Check internet connection stability
3. Clear browser cache if persistent
4. Try different browser

Display Problems

Problem: Images don't render correctly

Solutions:

1. Try different browser (Chrome/Firefox recommended)
2. Update browser to latest version
3. Disable browser extensions temporarily
4. Check graphics drivers on local machine