Two Paths To Accuracy
Every solar calendar must correct for the mismatch between day-cycles and year-cycles. HEKA offers two approaches: one for coordination, one for astronomical purity.
SYNC vs TRUE
SYNC Mode
Aligns with Gregorian leap years
March has 30 days when the Gregorian calendar has a leap year (Feb 29). HEKA April 1st realigns with Gregorian April 1st every year. Perfect for coordinating with the civil world.
Gregorian year is leap
Realignment:
April 1st, annually
- ✓ Matches civil calendar exactly
- ✓ April 1st always aligned
- ✓ Recommended for most users
TRUE Mode
Follows pure astronomical precision
Uses the "4-year, except 128th" rule. March has 30 days every 4 years, except every 128th year which has 29.
Year ÷ 4 = whole
EXCEPT year ÷ 128
- ✓ Astronomical precision
- ✓ Mean year: 365.242188 days
- ✓ For purists and long-term
The Difference Over Time
In daily life, you won't notice the difference between SYNC and TRUE. Over centuries, TRUE mode drifts from the Gregorian calendar by a tiny amount, about 1 day every 450,000 years. For most users, SYNC mode provides the best balance of astronomical accuracy and civil coordination.
Why 365.242188 Days?
This expression yields exactly 365 + 31/128, matching the tropical year (the time from one vernal equinox to the next).
The Components
The Result
The tropical year is approximately 365.24219 days. HEKA's TRUE mode achieves 365.24219, a difference of less than 0.00001 days per year.
How Calendars Measure Up
Julian
RomanGregorian
CivilHEKA
TRUE ModeTropical year: 365.2421897 days (IAU 2000 standard)