Day 4

Wrote more about how Greenwich Mean Sidereal Time as well as the local sidereal time can be obtained with the current code.

• https://git.sr.ht/~tagglink/celestial-navigation-tools/tree/main/item/wiki/gmst_calc.md
• https://git.sr.ht/~tagglink/celestial-navigation-tools/tree/main/item/wiki/altaz_to_lst.md