How to Download Swiss Ephemeris Asteroid Data Using a Python Script

How to Download Swiss Ephemeris Asteroid Data Using a Python Script

This guide provides a step-by-step walkthrough for using a Python script to download asteroid data from the Swiss Ephemeris, hosted on Dropbox. The script automates the download process, saving time and effort when dealing with large datasets that Dropbox does not allow to be downloaded all at once.

Prerequisites

• Python: Ensure Python is installed on your system.

• Basic Command Line Knowledge: Familiarity with using terminal commands.

• Dropbox Access: Obtain the Dropbox directory URL and the associated rlkey required for downloading files.

Step-by-Step Guide

1. Gather the Required Data

• Dropbox Directory URL: Navigate to the Swiss Ephemeris GitHub page and locate the Dropbox link for the asteroid data. The link should look something like https://www.dropbox.com/scl/fo/y3naz62gy6f6qfrhquu7u/h/long_ast.

• RL Key: This is a query parameter required by Dropbox to allow access to the files. It is usually part of the URL you obtain from Dropbox (e.g., rlkey=ejltdhb262zglm7eo6yfj2940).

2. Prepare the List of Asteroid Directories

• Go to the Dropbox page for the Swiss Ephemeris asteroid data.

• Copy the list of directories (each directory corresponds to a specific asteroid).

• Paste these directory names into a spreadsheet or text file, ensuring that each directory name is on a separate line.

• Save this list as a plain text file (e.g., input_file.txt). This file will be used by the script to know which directories to download.

3. Download the Python Script

• Access the Python script provided for downloading the files. You can download it using the link provided in the video description or from a shared location.

• Save the script to your working directory. The script might be compressed (e.g., in .gzip format). If so, decompress it using the following command:

  gunzip download_script.py.gz
  

4. Set Up Your Environment

• Open a terminal or command prompt.

• Navigate to the directory where you saved the Python script.

• Ensure you are in a Python virtual environment if necessary.

5. Run the Script

• The script requires four arguments:

  1. Input File: The text file containing the list of directories.

  2. Download Directory: The local directory where the files will be saved.

  3. Dropbox Directory URL: The base URL of the Dropbox directory (e.g., https://www.dropbox.com/scl/fo/y3naz62gy6f6qfrhquu7u/h/long_ast).

  4. RL Key: The Dropbox rlkey for access (e.g., ejltdhb262zglm7eo6yfj2940).

• Example command:

  python download_script.py input_file.txt ./downloads https://www.dropbox.com/scl/fo/y3naz62gy6f6qfrhquu7u/h/long_ast ejltdhb262zglm7eo6yfj2940
  

• If your rlkey or URL contains special characters, it is advisable to wrap them in quotes.

6. Monitor the Download Process

• As the script runs, it will download each directory specified in your input file.

• The script will create the download_dir if it does not already exist.

• Each asteroid file will be saved with a .zip extension.

7. Verify the Downloads

• Once the script completes, you can navigate to the download directory to ensure all files have been downloaded.

• If you encounter any errors during the download, the script will display the corresponding HTTP status codes.

8. Integrate with Swiss Ephemeris

• After all files are downloaded, move them to your Swiss Ephemeris data directory for use in your astrological calculations.

Troubleshooting

• Double Slashes in URLs: The script is designed to handle trailing slashes in the Dropbox URL automatically, so you don't need to worry about double slashes.

• Special Characters: If you have special characters in your rlkey, ensure they are correctly handled by placing the key in quotes.

• Slow Downloads: The download speed depends on your internet connection. Large datasets might take a while to complete.

Conclusion

By following this guide, you should be able to automate the download of large asteroid datasets from Dropbox using the provided Python script, saving you significant time and ensuring you have all the necessary data for your astrological work with the Swiss Ephemeris.

If you have any questions or encounter issues, feel free to reach out to Ryan Hunt for assistance. Happy downloading!

Link to script: https://drive.google.com/file/d/1dp0Dr_QXZUFqldgiPgwqk4QPNmvvXZco/view?usp=drive_link

Link to the Swiss Ephemeris: https://github.com/aloistr/swisseph?tab=readme-ov-file