Civil hour reference · 1991-10-21 · 05:00–07:00
October 21, 1991 · 05:00–07:00 (Mao hour · Rabbit)
The Mao hour · Rabbit double-hour (05:00–07:00) completes Monday, October 21, 1991 with a fourth, hour pillar: 辛未 · 戊戌 · 甲子 · 丁卯.
Answer first: the reference four pillars for 1991-10-21, 05:00–07:00, are year 辛未, month 戊戌, day 甲子, hour 丁卯. 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
1991-10-21 · 05:00–07:00 at a glance
| Gregorian date | Monday, October 21, 1991 |
|---|---|
| Double-hour | Mao hour · Rabbit · 05:00–07:00 civil clock · branch 卯 |
| Year pillar | 辛未 · Yin Metal Goat · Yin Metal over Earth |
| Month pillar | 戊戌 · Yang Earth Dog · Yang Earth over Earth |
| Day pillar | 甲子 · Yang Wood Rat · Yang Wood over Water |
| Hour pillar | 丁卯 · Yin Fire Rabbit · Yin Fire over Wood |
| Hour Na Yin | 炉中火 · hidden stems 乙 |
| 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 Goat · Xin Wei
The visible stem is Xin · Yin Metal; the branch is Wei · Goat · Earth. Its Na Yin is 路旁土, and the branch contains hidden stems 己 · 丁 · 乙. Open the full Jiazi record →
Yang Earth Dog · Wu Xu
The visible stem is Wu · Yang Earth; the branch is Xu · Dog · Earth. Its Na Yin is 平地木, and the branch contains hidden stems 戊 · 辛 · 丁. 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 Fire Rabbit · Ding Mao
The visible stem is Ding · Yin Fire; the branch is Mao · Rabbit · Wood. Its Na Yin is 炉中火, and the branch contains hidden stem 乙. 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 (05:00 or 07:00) 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 1991-10-21
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 1991-10-21 05:00–07:00
What is the hour pillar for 05:00–07:00 on Monday, October 21, 1991?
In this civil-clock reference, the 05:00–07:00 double-hour on 1991-10-21 carries the hour pillar 丁卯 (Yin Fire Rabbit), completing the four-pillar record 辛未 · 戊戌 · 甲子 · 丁卯.
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.