The most simple celestial navigation calculator. The idea is to still use a paper or digital Nautical Almanac like this one, but not to rely on Pub 249 or Pub 229 for sight reductions.
You could also use this notebook to make sure your manual calculations, or sight reduction with tables are correct.
Two things are offered by the calculator:
- First, you can simply reduce a sight using true formulas (more precise than sight reduction table and less prone to error), assuming your Dead Reckoning position as the assumed position (more precise and less prone to errors). You will still have to correct for your height and refraction using tables or formula given in the Nautical Almanac.
- Second, you can check the accuracy of your sextant using the angular distance between two celestial bodies (planets and stars preferably). No horizon is required for this check, so you can do it at home, even in some pretty light polluted areas.
You only need numpy to make it work. I let you decide which environment you may want (virtual environment for example). For reproducibility, note that I use numpy version 2.3.2.
All angles are manually entered as degrees, conversions to radians are handled automatically. If you enter radians, you will get wrong results.
Let’s be honest, this is the simplest celestial navigation calculator you could think of (and still much better than whatever you could find on the internet, although much more complete libraries could easily be found). I do not want you to improve it in any fancy way. Fell free to fork it and make your own contributions for yourself or others, but I like it the way it is now: very simple. The only contributions I would accept is if you were to correct formulas in any way, or propose another use case with other formulas.
For contributions, I would ask you to use the filter of the Python package nb-clean. This removes results and execution numbers from notebooks before staging (and committing and pushing) them.
Thank you. Open source is life!