ISS Bluesky Bot #

Bluesky bot that posts pass predictions for Sheffield, UK. Follow over at @isspassbot.bsky.social Fork of my satellite tracker project.

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What the Project Is #

• Tracks the ISS
• Makes pass predictions
• Posts on Bluesky

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How It Works #

• API call to Celestrak returns OMM JSON data.
• Propagates orbit forward from TLE epoch to current time.
• Converts coordinate frames into Earth latitude/longitude.
• Applies GST rotation to account for Earth's rotation.
• Computes observer position in Sheffield in ECEF and rotates into ECI using GST
• Projects satellite-observer difference vector in the local frame
• Calculate elevation and azimuth from difference vector
• Predicts future passes by iterating over future elevation/azimuth until a visible pass is found
• Posts to Bluesky

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Tech Stack #

• Languages: Python
• Libraries: requests
• Tools: Celestrak, Bluesky

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What I Learned #

• API calling
• Keplerian orbital mechanics
• Co-ordinate frame translation
• Orbital predictions
• AT Protocol basics
• GitHub Actions

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Project Structure #

├── LICENSE.md
├── README.md
├── main.py
├── poster.py
├── predictor.py
├── propagator.py
└── requirements.txt

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How to Run the Project #

git clone https://github.com/liampallett/iss-bluesky-bot.git
pip install -r requirements.txt
export BSKY_HANDLE="your-handle"
export BSKY_APP_PASSWORD="your-app-password"
python main.py

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Future Improvements #

• Only post about visible passes

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