caspy (Conjunction Analysis and Screening with Python) is Python software for ephemeris screening and conjunction analysis. caspy reads ephemerides from CCSDS OEM files and writes conjunction events to CDM files.

Installation

1. Install the orbdetpy https://github.com/ut-astria/orbdetpy develop branch.

2. Run pip install -r requirements.txt to install Python dependencies.

Usage

1. Run python caspy/cas.py for command line syntax. You can also import the caspy package and call the run_cas() function from your own Python code. The run_cas() arguments mirror the CLI parameters.

2. Space-Track publishes operator ephmerides in the "Modified ITC" format detailed in https://www.space-track.org/documents/Spaceflight_Safety_Handbook_for_Operators.pdf. Use utils/meme_to_oem.py to convert these files to OEM format.

3. Download the UT object catalog ID file to ensure caspy uses object identifiers consistently. The file must be updated frequently to account for launches etc. Provide the fully qualified file name in the environment variable CASPY_OBJECT_CATALOG before running caspy. For example:

export CASPY_OBJECT_CATALOG=$HOME/object_catalog.csv

curl -o $CASPY_OBJECT_CATALOG http://astria.tacc.utexas.edu/AstriaGraph/OD_stats/object_catalog.csv

Docker

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You will first need to clone orbdetpy and build its docker image as posted here.

docker build -t caspy:core .
docker run --rm caspy:core -h

Examples

1. examples/tle_cas.py demonstrates TLE screening functionality.