Constant hifitime::J1900_OFFSET

pub const J1900_OFFSET: f64 = 15_020.0;

J1900_OFFSET determines the offset in julian days between 01 Jan 1900 at midnight and the Modified Julian Day at 17 November 1858. NOTE: Julian days "start" at noon so that astronomical observations throughout the night happen at the same Julian day. Note however that the Modified Julian Date (MJD) starts at midnight, not noon, cf. http://tycho.usno.navy.mil/mjd.html.