These files contain geometries outlining the Milky Way isophotes at five levels of surface brightness.
The files are based on the one provided on the d3-celestial plugin by Olaf Frohn with cleanup by Diego Hernangómez.
For mw.json, using geojson.io I reworked manually the polygons at the -180º=180º RA boundary to avoid large gaps.
For mw_simplified_43p.json I also used mapshaper.org simplify command with percentage=43%. This allowed for a >50% reduction in file size with very little degradation of the polygons.
For mw_simplified.json, simplify command was used with percentage=9%. The degradation on the polygons is quite acceptable for smaller maps, and the file size is reduced to 10%.
The files were exported with mapshaper.org back to GeoJSON using the parameter precision=0.001 as the original.
id: Milky Way outlines in 5 brightness steps (ol1-ol5).
Frohn O, Hernangómez D (2023). “Celestial Data.” doi:10.5281/zenodo.7561601 https://doi.org/10.5281/zenodo.7561601, https://dieghernan.github.io/celestial_data/.