alelouis / lst

Minimalist LST (Local Sidereal Time) displayer for star gazers.

Local Sidereal Time

Small utility app written in Rust computing your LST (Local Sidereal Time) at your longitude.
LST is based on Earth's rotation with respect to the stars and not the sun (hence a faster running clock).

How to use

gh repo clone alelouis/lst
cargo run --release

Algorithm

• Get UTC time
• Compute Julian UTC Date (should be UT1)
• Compute ERA from JD
• Compute GMST from ERA (not really*)
• Compte LST from GMST and local longitude

Main steps are implemented under src/app/lst.rs.

Todo

• Use UT1 instead of UTC for JD
• *Compensate GMST for precession and nutation

References

• https://en.wikipedia.org/wiki/Universal_Time
• http://www.jgiesen.de/astro/astroJS/siderealClock/
• https://en.wikipedia.org/wiki/Sidereal_time#ERA

Dependencies

rust egui chrono hifitime