Case 08 of 26
Historical time zones
Chicago 1990: western longitude plus DST
A North American historical record exercises a negative UTC offset and summer time.
Boundary question
Can the same wall-clock noon be normalized with America/Chicago history?
Yes. The record uses UTC−05:00 with a 60-minute DST component and corrects to 11:09 true solar time.
Synthetic input
Recorded facts
- Date
- 1990-06-15
- Recorded time
- 12:00
- Location
- Chicago, United States
- Time zone
- America/Chicago
- Longitude
- -87.6298°
- Gender input
- Female
Pinned expected facts
Verified output
Year
庚午
Month
壬午
Day
辛亥
Hour
甲午
- Day Master
- 辛
- True solar time
- 1990-06-15 11:09
- Total correction
- -50.55 minutes
- Historical offset
- UTC−05:00 · DST 60 min
- Luck direction
- 逆排
- Reference Jie
- 芒种 · 1990-06-06 06:46:18
- Luck start
- 1993-07-07 09:27:27
Conventions and limits
What this case does — and does not — prove
It verifies
Deterministic reproduction of this input under the named engine version and conventions. A pinned-field mismatch stops the production build.
It does not claim
Universal agreement across Bazi schools, interpretation of a real person, or certainty where the historical record is incomplete.
tyme4ts 1.5.2 · cantian-tymext 0.0.27 · sect 2 day boundary · BaziCalculator.ai NOAA/IANA true-solar adapter
calculation-benchmarks-v1 · reviewed 2026-09-05