Note: The sunrise and sunset results are theoretically accurate to within a minute
 for locations between +/- 72° latitude, and within 10 minutes outside of those latitudes.
 However, due to variations in atmospheric composition, temperature, pressure and conditions,
 observed values may vary from calculations.
...
Please note that calculations in the spreadsheets are only valid for dates between 1901 and 2099,
 due to an approximation used in the Julian Day calculation."