Low Frequency Extensions of Cyclotron Maser Instability-Generated Radio Emission: A Statistical View from Cassini at Saturn

• Authors: Caitríona M. Jackman, Alexandra R. Fogg, Stan W.H. Cowley, Gabrille Provan, Hanna Adamski, Nathan M. Besch, Simon Walker, Matthew J. Rutala, Daragh M. Hollman, Laurent Lamy, Elizabeth P. O'Dwyer

This is the codebase for Jackman et al. (2025), please follow the instructions below to reproduce the figures of the paper. If you only want to access the data find it here.

Installation Steps (recommended)

Requirements: git, Python 3.13.1+, environment management system for Python (conda, pyenv...)

Clone the repository in your desired directory:

git clone https://github.com/DIASPlanetary/Saturn_LFEs.git

We recommend creating a new Python 3.13.1+ environment using your preferred tool. Go into Saturn_LFEs and install the required project packages in your newly created environment:

pip install --upgrade pip
pip install -r requirements.txt

Download calculated files

Please download the data from and place the files in data/calculated/.

Additionally you will need the Yearly raw Saturn Kilometric Radiation (SKR) files to be placed in data/raw/SKR_raw.

Download raw files

These files are to be placed in data/raw/

• Yearly raw Saturn Kilometric Radiation (SKR) files containing the flux information for the duration of the Cassini mission. Place them in data/raw/SKR_raw/.
• Low Frequency Extensions (LFEs) catalogue containing LFE start and stop times as well as polygon vertices on the flux map from SKR raw data. Also has a csv file containing start and stop times of LFEs.
• Phase information

This is all the setup that is required to reproduce the figures inside fig folders. If you want to re-create the calculated files, check the next section.

Data Processing

Please run all python scripts from the Saturn_LFEs directory, otherwise the relative file paths will not work.

To be able to re-create the calculated files i.e. the new LFE catalogue, you will need to download the raw files as stated above as well as setting up SPICE kernels, and then run python scripts in data_processing/. Details below.

SPICE

If you're familiar with using SPICE and spiceypy - and have your own metakernel - you can skip to the end of this section and replace the path with a path to your metakernel. Otherwise please follow the instructions below:

To use spiceypy to quickly retrieve Cassini ephemeris we must download the relevant SPICE kernels. AutoMeta (Rutala, M. J.) is a great package for easily downloading the required kernels without needing any experience with SPICE. In Saturn_LFEs directory execute this command:

git clone https://github.com/mjrutala/AutoMeta.git

Then run:

python Autometa/autometa/make_Metakernel.py

And when prompted with typing the name of the spacecraft simply type:

Cassini

And press Enter. Then press Enter again to download the SPICE folder at the root directory of Saturn_LFEs.

This will download the Cassini kernel files (~3 GB) in a SPICE folder at the root of the project. When finished, you will find a subdirectory SPICE/Cassini/ which will contain metakernel_cassini.txt.

Final Steps

Run get_ephemeris.py, join_lfes.py, add_ppos.py, join_json.py and get_polygon_flux.py in that order to recreate the files in data/calculated/.