I'll just add that there are also non-novelty firmwares available - alternate timebase clocks. I have Martian, Sidereal, Tidal, Lunar, weekly, annual and quadre

I'll just add that there are also non-novelty firmwares available - alternate timebase clocks. I have Martian, Sidereal, Tidal, Lunar, weekly, annual and quadrennial clocks.