Civil hour reference · 2001-12-27 · 21:00–23:00
December 27, 2001 · 21:00–23:00 (Hai hour · Pig)
The Hai hour · Pig double-hour (21:00–23:00) completes Thursday, December 27, 2001 with a fourth, hour pillar: 辛巳 · 庚子 · 甲子 · 乙亥.
Answer first: the reference four pillars for 2001-12-27, 21:00–23:00, are year 辛巳, month 庚子, day 甲子, hour 乙亥. The hour stem is derived from the day stem by the standard five-rat rule. This is a deterministic calendar record, not a personal reading.
Deterministic record
2001-12-27 · 21:00–23:00 at a glance
| Gregorian date | Thursday, December 27, 2001 |
|---|---|
| Double-hour | Hai hour · Pig · 21:00–23:00 civil clock · branch 亥 |
| Year pillar | 辛巳 · Yin Metal Snake · Yin Metal over Fire |
| Month pillar | 庚子 · Yang Metal Rat · Yang Metal over Water |
| Day pillar | 甲子 · Yang Wood Rat · Yang Wood over Water |
| Hour pillar | 乙亥 · Yin Wood Pig · Yin Wood over Water |
| Hour Na Yin | 山头火 · hidden stems 壬 · 甲 |
| Zi-hour convention | Early Zi: the 23:00–01:00 double-hour is anchored to this civil date at 00:00. The late-Zi school (23:00–24:00 → next day) is a documented boundary below. |
Four coordinates, four jobs
What the four reference pillars contain
Each stem-branch pair is a deterministic calendar coordinate. The hour pair inherits its branch from the double-hour and its stem from the day stem, so it stays consistent with every other hour page of this date.
Yin Metal Snake · Xin Si
The visible stem is Xin · Yin Metal; the branch is Si · Snake · Fire. Its Na Yin is 白蜡金, and the branch contains hidden stems 丙 · 庚 · 戊. Open the full Jiazi record →
Yang Metal Rat · Geng Zi
The visible stem is Geng · Yang Metal; the branch is Zi · Rat · Water. Its Na Yin is 壁上土, and the branch contains hidden stem 癸. Open the full Jiazi record →
Yang Wood Rat · Jia Zi
The visible stem is Jia · Yang Wood; the branch is Zi · Rat · Water. Its Na Yin is 海中金, and the branch contains hidden stem 癸. Open the full Jiazi record →
Yin Wood Pig · Yi Hai
The visible stem is Yi · Yin Wood; the branch is Hai · Pig · Water. Its Na Yin is 山头火, and the branch contains hidden stems 壬 · 甲. Open the full Jiazi record →
Calculation boundary
What this hour reference does not settle
This page uses a standard civil clock so double-hours can be compared consistently across dates. A real birth happened at a place and an instant, not inside a URL slug.
- True solar time: the reference assumes a standard-meridian civil clock. Birthplace longitude and the equation of time shift the effective hour, and can move the resolved pillar to a neighboring double-hour.
- Hour boundary: a clock time within the correction margin of an odd-hour boundary (21:00 or 23:00) is boundary-risk until resolved against place.
- Zi-hour school: the 23:00–01:00 slot follows the early-Zi convention. Late-Zi schools push 23:00–24:00 onto the next day pillar; neither this page nor the atlas settles that debate.
- Interpretation: one four-pillar record does not determine personality, career, relationships, wealth, health, or events. It is a coordinate, not a verdict.
All twelve double-hours of 2001-12-27
Resolve your actual hour pillar
Calculate the real birth chart
Add birth time and birthplace. Pillarwise resolves historical timezone, longitude correction, equation of time, and hour-boundary risk before it fixes the hour pillar — this reference page is only the civil-clock starting point.
Questions about 2001-12-27 21:00–23:00
What is the hour pillar for 21:00–23:00 on Thursday, December 27, 2001?
In this civil-clock reference, the 21:00–23:00 double-hour on 2001-12-27 carries the hour pillar 乙亥 (Yin Wood Pig), completing the four-pillar record 辛巳 · 庚子 · 甲子 · 乙亥.
Why does the Zi hour list 23:00–01:00 as one range?
The Zi double-hour spans midnight in the classical two-segment form 23:00–01:00. This reference adopts the early-Zi convention: 00:00–01:00 belongs to the same civil date. Schools that use the late-Zi convention assign 23:00–24:00 to the next day pillar, which can change both the day and hour pillar; that difference is an open school boundary, not an error.
Is this my personal hour pillar?
Not necessarily. This page is a civil-clock reference at a standard meridian. A personal chart resolves your birthplace longitude, historical timezone, and true solar time, and any of those corrections can move the resolved hour pillar to a neighboring double-hour.
What happens near an hour boundary?
A clock time within the correction margin of an odd-hour boundary (01:00, 03:00, … 23:00) can resolve to the adjacent double-hour once longitude and equation-of-time corrections are applied. Use the calculator to see the resolved pillar and its boundary-risk flag.