Many of our project projects here at Duke use a program called GalSim.
https://github.com/GalSim-developers/GalSim
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There is enough information in the text to figure out how to make this. But one thing: there is no easy way to make a galaxy on its “edge” so just make galaxies from the front with about the correct size and aspect ratio and make them the proper distance apart. Go ahead and add stars.
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