The nakshatra sub-lord: nine unequal slices, and why the Ascendant's needs your birth time to the minute

A nakshatra is 13 degrees 20 minutes of sky, one of 27 equal divisions of the zodiac, and your birth nakshatra is the one your Moon occupied. It can be cut again. Split into nine unequal slices by the same years that run the Vimshottari Dasha, it gives every point in a chart a lord below its nakshatra lord: the sub-lord. Unlike your nakshatra, this site will not compute it from a birth date alone, for reasons that can be measured on the Moon and the Ascendant.

How the nakshatra is split

The nine lords and their years are the constants the Vimshottari Dasha runs on, unchanged. A nakshatra is 800 arcminutes wide, and each lord gets a share in proportion to its years out of 120. Venus, with 20 years, gets a sixth. The Sun, with 6, gets a twentieth.

The rotation matters. Each nakshatra's first slice belongs to its own lord, so Ashwini's slices open with Ketu and Krittika's with the Sun. That mirrors the rule for sub-periods in time, which Brihat Parashara Hora Shastra (BPHS) states as "the first Antar Dasha belongs to the Lord of the Dasha" (Ch. 51, Sloka 2). A table starting every nakshatra at Ketu, the mistake this engine's tests guard against, is wrong for 24 of the 27. Nine slices in each of 27 nakshatras makes 243 around the zodiac.

A worked example

The engine's own test case is the Ascendant for 15 August 1947, 00:00 IST, New Delhi: 37.73 degrees sidereal, inside Krittika, which begins at 26 degrees 40 minutes. That is 664 arcminutes into the nakshatra. Krittika's slices start from the Sun, and their running totals are Sun 40, Moon 106.67, Mars 153.33, Rahu 273.33, Jupiter 380, Saturn 506.67, Mercury 620, Ketu 666.67 and Venus 800. 664 falls between 620 and 666.67, so the sub-lord is Ketu, 2.58 arcminutes short of Venus.

A second example, every row of one chart

The 1947 Ascendant is the engine's test case. Here is a whole chart instead: the birth on 15 August 1990 at 10:30 IST in New Delhi that the Mahadasha essay works through. The Moon is at 48.92 degrees, 535.3 arcminutes into Rohini. Rohini is a Moon nakshatra, so its slices start from the Moon:

So the Moon's sub-lord is Mercury, 68.6 arcminutes past the start of its slice and 44.69 short of Ketu's. At the Moon's speed of roughly half a degree an hour, that is a margin of about two hours behind and an hour and a half ahead: a birth time known to the nearest half-hour settles it. The full table the calculator returns for this birth is:

Read the distance column the way the page recommends and three things stand out. The Ascendant sits in Chitra's Saturn slice, about 50 arcminutes past its start and 77 short of its end. At roughly 15 arcminutes of Ascendant per clock minute, that is a window of about three minutes before the recorded time and five after: a birth recorded as "10:30" that was really 10:25 or 10:36 has a different Ascendant sub-lord. Ketu sits under 8 arcminutes from its next boundary, and Venus about 15. Venus's own position is checked to about an arcminute, but both gaps are inside the range a different ayanamsa could move them, and Ketu's also depends on which node is used. Those two rows are not settled by any birth time. The Moon, the Sun, Jupiter and Rahu are comfortably inside their slices.

The slow rows are a reminder of the other side of the measurement above. Jupiter in this chart is 101.67 arcminutes from its next boundary and Rahu 67.88. Jupiter moves about a sixth of a degree a day and Rahu about a twentieth, so neither row would change if the birth time were wrong by a whole day; Rahu would need about three weeks. For these points the birth time is irrelevant and the only real uncertainties are the ayanamsa and the computed position. Saturn, at 34.78 arcminutes, is safe against time and closer to the zone where those other uncertainties begin to matter. Mercury, at 26.34 arcminutes and moving about a degree a day, would hold for roughly eleven hours of lateness - safe against any ordinary time error, and far outside the arcminute or so the project documents for its Mercury, though not outside the spread between ayanamsas.

Notice also how often Ketu appears as the "next" lord. That is not chance: in every nakshatra the slice after Mercury's is Ketu's, because Ketu follows Mercury in the cycle, and Mercury's slice is one of the wider ones. Points that sit in a Mercury slice will always report Ketu next.

What the classical citation covers, and what it does not

BPHS supplies the lords and their years (Ch. 46, Slokas 12-15) and the rule for splitting a dasha period among them in proportion (Ch. 51, Slokas 1-2). Those are rules about time. BPHS never divides a nakshatra's arc into nine, and a full-text search of the edition in this project's library finds no "sub-lord" at all. Applying the time rule to arc is an extension of it, not a use of it, and the calculator page says so. The lords, the years and the proportions are sourced; applying them to arc, and the name, are not.

Why it needs your birth time, measured

The Moon moves about 13.2 degrees a day, and the 243 slices average 88.9 arcminutes, just under 1.5 degrees. Run through this engine for 535 birth days spread from 1960 to 2019, the Moon changed sub-lord between 7 and 12 times within the day, 9 at the median, and on none of those days did it stay in one slice from midnight to midnight. In a continuous run through 1990 and 1991, a slice held the Moon for between about one and four and a half hours.

The Ascendant is far faster. The whole zodiac rises once a day, so all 243 slices cross the horizon daily. Measured at Delhi, Mumbai, Chennai and Kolkata on four dates in 2026, it stayed in one slice for between 1.8 and 10.5 minutes, about 6 at the median.

So without a time the calculator reports no sub-lord at all, not a weaker one, and says so instead of assuming noon. A birth place adds the Ascendant's row, but only one that resolves to real coordinates, never an Ascendant computed for latitude zero. A time rounded to the nearest fifteen minutes can be seven and a half minutes out, longer than the Ascendant usually stays in one slice. If your record has no time at all, what an unknown birth time costs sets out which parts of a chart survive without one. The Moon's and the Ascendant's sub-lords are not among them. The slow points usually are: over the same 535 days, the sub-lords of Jupiter, Saturn, Rahu and Ketu held from midnight to midnight on 90 to 97 percent of them. The calculator still asks for a time before it shows any row.

Why the Ascendant's window is 2 to 10 minutes

The measured dwell times above - 1.8 to 10.5 minutes in one slice - follow directly from the slice widths and the speed of the rising sign. The narrowest slice is the Sun's, 40 arcminutes; the widest is Venus's, 133.33. At the average Ascendant speed of about 15 arcminutes a minute, those take about 2.7 and 8.9 minutes to cross. Fast-rising signs shorten every slice and slow-rising ones lengthen it - at New Delhi the quickest sign rises in about 85 minutes and the slowest in about 140, as the birth-time essay measures - so a Sun slice in a quick sign can pass in under two minutes and a Venus slice in a slow one can take over ten. That is the whole range of the measurement, explained by two numbers.

What happens at a nakshatra line

Because every nakshatra starts its slices with its own lord and runs through the cycle, its last slice always belongs to the lord just before its own. Rohini, a Moon nakshatra, ends in a Sun slice; Mrigashira, the Mars nakshatra after it, begins with a Mars slice. So as a point crosses from one nakshatra into the next, the sub-lord jumps from the lord before the old nakshatra's lord to the lord after it - Sun to Mars at the Rohini-Mrigashira line - skipping the old nakshatra's own lord. The same pattern holds at all 27 lines.

At three of those lines - 0, 120 and 240 degrees, the starts of Aries, Leo and Sagittarius - the sign also changes. A point sitting there is on a sign line, a nakshatra line, a pada line and a sub line at once, and any small difference between two calculations changes all four labels together. These are the places where two apps' charts look most different for the smallest underlying difference; why apps disagree on your nakshatra works one such case, a 1995 Moon six arcminutes past the 120-degree line.

Two ways of cutting a nakshatra: pada and sub

A nakshatra is already divided once in the classical system: into four equal padas of 200 arcminutes. The sub-lord division is a different kind of cut, and it helps to keep them apart. The pada is equal; the sub is proportional. The pada is tied to the signs - every pada is exactly one Navamsa, so the 108 padas of the zodiac are the 108 Navamsa divisions, and the pada is how the nakshatra connects to the Navamsa chart. The sub is tied to the dasha - its proportions are the Vimshottari years - and its boundaries generally do not line up with the pada lines at all.

So the sub-lord is finer than the pada, but not uniformly: a Sun slice is a fifth of a pada, a Venus slice two thirds of one. And the two grids are independent enough that a point can be safely inside its pada and right on the edge of its sub, or the other way round. The 1990 Ketu, 7.88 arcminutes from a sub boundary, is an example: it is a point whose Navamsa a small error would not change but whose sub-lord it easily could.

How good is the engine's Moon at this scale?

The sub-lord of the Moon is only as good as the Moon's longitude, and the project's own documentation rates its Moon at 0.1 to 0.3 degrees - 6 to 18 arcminutes, a sizeable fraction of a slice. That rating is a stated bound, not a measurement, so it is worth asking whether an external check exists. One does, indirectly.

Advanced Predictive Astrology, a case-study book in the project's library, prints each chart with its "balance of dasa" at birth: the years, months and days of the first Mahadasha left. That balance is a direct function of the Moon's position within its nakshatra - the same proportion this page uses for arc - and the book states that it used the Lahiri ayanamsa. So running the same births through this engine and comparing balances is a check on the Moon.

In all six the engine names the same first lord, and the balances agree to within a few days, which corresponds to Moon positions within about an arcminute of each other. Six charts are not a proof, the book's own software is of unknown precision, and the month convention adds its own few days of slack - so this page keeps the documented 0.1 to 0.3 degree bound as the official figure. But the comparison does suggest the bound is conservative for ordinary charts, and that a Moon row more than 20 arcminutes from its boundary is very unlikely to be moved by the lunar model.

The sub-lord is not the Antardasha at birth

Because the sub-lord uses the same proportions in arc that the Antardasha uses in time, it is tempting to say the Moon's sub-lord "is" the Antardasha you were born in. In this engine it is not, and the reason is a convention explained in Antardasha and Pratyantar. This engine divides the shortened first Mahadasha - the part left after birth - among all nine lords, starting with the Mahadasha lord. So its Antardasha at birth is always the Mahadasha lord itself. In the 1990 chart, the Moon's sub-lord is Mercury, but the engine's Antardasha at birth is the Moon.

Under the other convention - full-length sub-periods, entered part-way through - the Antardasha running at birth would be the slice the Moon occupies, and the two would coincide. Both conventions are in use and this page does not choose between them; it only warns against reading the sub-lord calculator as a statement about your birth Antardasha on this site, because here it is not one.

Where the idea comes from, as far as this library can say

It is worth being exact about the provenance, because the sub-lord is often presented as ancient. In the books this project works from, it is not. BPHS gives the nine lords, their years, and the rule that divides a period of time among them; it divides arc only into signs, nakshatras and padas. Bhrigu Sutras and the prashna text in the library do not divide a nakshatra into nine either. Saravali uses the phrase "sub-Lords" once, but for the lords of sub-periods of time within a dasha, not for slices of a nakshatra - the same time-based idea BPHS has, under another name. The one book in the library that mentions sub-lords at all is the modern one, Advanced Predictive Astrology, and only in passing: its preface says its computer-cast charts list the "Sub lord" among other details for the benefit of "K.P. followers". It does not use sub-lords in its own case analyses.

So the honest description is the one the calculator gives: the division is the BPHS time rule carried over to arc, which is how KP practice defines its sub-lords, computed here with this app's Lahiri ayanamsa. Whether the extension is justified is a question about KP, not about BPHS, and this page leaves it there.

Why this is not KP

Krishnamurti Paddhati (KP) uses sub-lords, but this is not KP, and the first reason is a number. KP uses its own ayanamsa - its own figure for the offset between the tropical and sidereal zodiacs - and this project's library contains no numeric value for it. So the calculator uses Lahiri (Chitrapaksha), the only ayanamsa this code implements and the one every other astrology calculation here uses, and prints the model and its value for your birth moment.

At this scale that is not cosmetic. With boundaries 88.9 arcminutes apart on average, shifting the ayanamsa by D arcminutes changes the sub-lord on D/88.9 of the zodiac: about 1.1 percent of positions per arcminute. On the 1947 chart above, two of ten points sit within 3 arcminutes of a boundary - the Ascendant at 2.58 and Rahu at 2.27 - so an ayanamsa 3 arcminutes smaller would change both. The ayanamsa calculator shows the Lahiri value used for any date. KP also reads the sub-lords of house cusps; this product draws whole-sign houses and computes no cusps, so there is no cusp row here.

What the result tells you, and what it does not

• For the Moon, Sun, Mars, Mercury, Jupiter, Venus, Saturn, Rahu and Ketu, plus the Ascendant when a place resolves: the nakshatra, its lord, the sub-lord, the next sub-lord and the distance to it in arcminutes.
• All nine slices of your Moon's nakshatra with their start, end and width, so the arithmetic above can be checked on your own chart.
• Read the distance before the lord, and note that it is measured forward only: a point that has just entered its slice shows a large distance yet sits close to the boundary behind it. For the Moon, the slice table's start values show that side too. The Ascendant moves about 15 arcminutes per clock minute on average, so one a few arcminutes from a boundary is not settled even by a time to the minute. This project's documentation gives its Moon position as accurate to 0.1 to 0.3 degrees (6 to 18 arcminutes), so a Moon row nearer an edge than that is not settled either.
• No interpretation. The sources this product is built from supply no reading of what a sub-lord means, so the calculator shows the slice and stops there. It makes no prediction from it.

Converting the distance column into minutes

The calculator gives distances in arcminutes because that is what the arithmetic produces. What you usually want to know is how wrong your birth time could be before the answer changes. Two conversions cover almost everything.

• For the Moon: it moves about half an arcminute per clock minute (roughly 29 to 38 arcminutes an hour). So each arcminute of distance is worth about two minutes of birth time. A Moon 44.69 arcminutes from its next boundary, as in the 1990 chart, survives a time about an hour and a half late.
• For the Ascendant: it moves about 15 arcminutes per clock minute on average, faster in quick-rising signs. So each arcminute is worth about four seconds of birth time. An Ascendant 77 arcminutes from its next boundary survives about five minutes of lateness - and no more.
• For the slow planets: hours or days of birth-time error do not move them meaningfully; their distance matters only against ayanamsa and model differences, which are fixed for the chart.

Remember the warning in the list above: the distance is measured forward only. For a point that has just entered its slice, the boundary that matters for an early birth time is the one behind it, which only the Moon's slice table shows. For the 1990 Moon, that rear boundary is 68.6 arcminutes back - about two hours and twenty minutes of birth time. For the Ascendant you can work the rear distance out from the slice widths in the first table: subtract the forward distance from the width of the slice it is in.

1. 1.Find your birth time on a primary record if you can, and note how it is written - "10:30" may mean anything from 10:25 to 10:35.
2. 2.Run the calculator with that time and your birth place.
3. 3.For each row you care about, convert the distance to minutes with the rates above, and estimate the rear distance where you can.
4. 4.If your recorded time's uncertainty is smaller than both margins, the sub-lord is settled by the time. If not, say so when you use it.
5. 5.Separately, if the forward distance is under about 18 arcminutes, treat the row as unsettled whatever the time, because the model and ayanamsa uncertainties are that large.

Finding yours

The calculator needs a birth date and a birth time, ideally from a hospital record; a birth place adds the Ascendant. Read the distance column first.

For the layers above the sub-lord, which need less precision, the nakshatra calculator works from a date alone, the Lagna calculator gives the Ascendant's sign and degree, and the Navamsa calculator gives the pada-level division. The planet pages - for instance the Moon and Mercury - describe what the classical texts say about each planet, which is where interpretation on this site lives; the sub-lord calculator itself adds none.

Is the sub-lord in Brihat Parashara Hora Shastra?

No. BPHS gives the lords, their years and the proportional split of a dasha period. It never divides a nakshatra's arc into nine, and the word does not appear in the edition this project uses. The division here applies the BPHS time rule to arc.

Why will the calculator not give me a sub-lord from my birth date alone?

Because on every one of 535 sampled days the Moon changed sub-lord between 7 and 12 times. Any single answer from a date alone would be a guess, and the calculator reports nothing rather than a guess.

Will my sub-lords match a KP astrologer's?

For points far from a boundary, usually. KP uses its own ayanamsa, which this app does not implement, and at the sub level each arcminute of ayanamsa difference changes the answer on about 1.1 percent of the zodiac. Points near a boundary can differ.

Is the Moon's sub-lord the Antardasha I was born in?

Not on this site. This engine divides the shortened first Mahadasha starting from the Mahadasha lord, so its Antardasha at birth is always the Mahadasha lord. Under a convention that keeps full-length sub-periods, the two would coincide.

My birth certificate says 10:30. How precise is that?

Often less than it looks. Times are commonly rounded to the nearest five or fifteen minutes, so "10:30" can mean anything from about 10:23 to 10:37. That is comfortably precise enough for the Moon's sub-lord in most charts and usually not precise enough for the Ascendant's.

Why are some slices so much wider than others?

Each lord's slice is proportional to its Vimshottari years. Venus, with 20 years, gets 133.33 arcminutes; the Sun, with 6, gets 40. The unevenness is inherited directly from the dasha.

What does my sub-lord mean?

This site does not say. None of the classical sources it is built from gives a reading for a sub-lord, so the calculator shows the slice, the distances and the arithmetic, and stops.