* Prefix replacement keys with `$` in SatSim configuration file. * Add option to scale collision fragments by cosine of the exit angle.
0.8.1
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* Add astrometric metadata into FITS header * Refactor WCS library * Add option to flip images about x or y axis * Add option to refresh stars for each frame * Add RPO from TLE generator
0.8.0
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* Add two body propagator * Add object `create`, `delete`, and `update` events * Add collision generator * Add breakup generator * Add `ref` keyword to configuration * Add `key` keyword to `import` configuration * Refactor astrometric library
0.7.2
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* Add option to specify star and obs velocity in polar coordinates
0.7.1
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* Add option to turn off shot noise: `sim.enable_shot_noise: true` * Add option to turn off annotation boxes in image: `sim.show_obs_boxes: true` * Add option to specify velocity in arcseconds: `sim.velocity_units: arcsec` * Fix PNG output threading issue