Nakshatra Sub-Lord

The panel above returns a table: each point in your chart, its nakshatra, the lord of that nakshatra, the sub-lord beneath it, and how many arcminutes separate the point from the next boundary. The paragraph over the form says in outline where the split comes from. This long read sets out the verses of Brihat Parashara Hora Shastra (BPHS) that supply the numbers, the exact steps the engine takes, a complete worked chart in which every figure was produced by the real engine, how to read each column and each kind of result, how fast the answer moves with the clock on one real day, and what this page deliberately does not compute.

The verses the nine slices come from

Nothing in this calculator uses a number of its own. The nine lords, their order and their years are those of the Vimshottari Dasha, which BPHS introduces in Ch. 46. Parashara lists many dasha systems there and says in Sl. 2-5 that Vimshottari is the most appropriate for people in general, with the others kept for special cases; the alternate dashas calculator covers the ones this app has built. Sl. 12-14 give the lords in order counted from Krittika - Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury, Ketu, Venus - and the rule that the birth nakshatra, counted from Krittika and divided by nine, names the lord whose period is running at birth. The same passage gives the reason for the total: a natural human life-span is taken as 120 years.

Sl. 15 gives the years: 6, 10, 7, 18, 16, 19, 17, 7 and 20, in that order. They add up to 120. Ch. 51 then says how a period is divided. Sl. 1: to find the span of one graha's Antardasha inside another's Dasha, multiply the two grahas' Dasha years and divide by the total years of all the grahas. Sl. 2 fixes the order: 'the first Antar Dasha belongs to the Lord of the Dasha', the other eight follow in the usual sequence, and the same applies one level down, to the Pratyantardasha. Ch. 61 Sl. 1 repeats the division by 120 for that third level. Inside a Mahadasha walks through those levels as dates.

That caption is the limit of the citation. Sl. 16 comes closest to arc, because it ties the Moon's place in its nakshatra to how much of the first period has run - but it speaks of the Moon's stay, which is a duration, and only of the Moon. BPHS never cuts the 13 degrees 20 minutes of a nakshatra into nine pieces, never applies the idea to the Ascendant or to another graha, and does not contain the term sub-lord. Laying the Ch. 51 proportions along the arc is an extension of the text's rule. The lords, the years and the proportions are Parashara's; the arc reading is a later construction that this calculator computes and shows without claiming classical authority for it. BPHS is listed with the app's other texts on the sources page.

The word does occur once elsewhere in this app's library, with a different meaning. Saravali Ch. 42 Sl. 1-3 shares out the sub-periods of its Moola Dasa by placement: a graha joined with the Dasa lord takes half, one in the 5th or 9th from it a third, one in the 7th a seventh, one in the 4th or 8th a quarter, and the translation calls those grahas the sub-lords of their sub-periods. That is a lord of a stretch of time, chosen by where grahas stand, not a slice of sky set by fixed years. The two texts do not agree on how a period is shared out, and neither divides a nakshatra.

Sign, nakshatra, pada, sub: four grids on one circle

A sidereal longitude can be cut at several grains. It helps to see them side by side before reading a result.

The pada is the classical cut below the nakshatra: four equal quarters, which the nakshatra calculator reports for the Moon. A quarter of a nakshatra and a ninth of a sign are the same 3 degrees 20 minutes, and both grids start from 0 degrees of Aries, so the 108 padas are also the 108 divisions of the Navamsa, the ninth-part chart BPHS defines in Ch. 6 Sl. 12. The sub is a different kind of cut. It is unequal, it is finer than a pada by a factor of 2.25 on average, and no divisional chart in this app's sources is built on it.

The grids do not nest neatly. Pada boundaries fall at 0, 200, 400 and 600 arcminutes into a nakshatra; sub boundaries fall wherever the running total of the years puts them, so one pada can hold parts of several slices and one wide slice can lie across two padas. Sign boundaries are ignored altogether. Sign and nakshatra boundaries coincide only at 0, 120 and 240 degrees, so nine of the 27 nakshatras lie across two signs, and a slice inside one of them can begin in one sign and end in the next. The worked example below contains one.

The calculation, step by step

The engine function is nakshatraSubdivision() in the server's astrology module, called once for each point by subLordTable(). In order:

1. 1.The birth date and time become one instant in UTC. If a place was chosen, its time zone, with the daylight-saving rule in force on that date, sets the clock. If no place resolves, the time is read as Indian Standard Time and the result records that the zone was assumed.
2. 2.Tropical longitudes are computed for that instant: the Sun and Moon from Meeus-series formulas, the five planets from the same astronomy module, Rahu as the Moon's mean node and Ketu exactly 180 degrees from it. With a resolved place, the rising degree is computed from the sidereal time at the birth longitude and the latitude.
3. 3.The Lahiri (Chitrapaksha) ayanamsa for that instant is subtracted from each: 23.85306 degrees at the J2000 epoch plus 0.0139601 degrees for every year since, about 50 arcseconds a year.
4. 4.Each sidereal longitude is rounded to four decimal places - 0.36 of an arcsecond - and that published value, the one every other page shows for the point, is the input.
5. 5.The longitude is divided by 13 degrees 20 minutes and rounded down. The whole number, 0 to 26, is the nakshatra counted from Ashwini; the remainder is how far into it the point sits.
6. 6.The nakshatra's number modulo nine picks its lord from the fixed cycle Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury. That lord owns the first slice.
7. 7.Walking the cycle from that lord, each slice ends at 800 arcminutes times the years counted so far, divided by 120. The first slice whose end lies beyond the point is its sub.
8. 8.The row reports the sub-lord, the distance from the point to the end of that slice, and the lord of the slice after it. After a ninth slice, the next lord is the first slice of the following nakshatra.

Step 7 computes every boundary from the running total of years, not by adding widths one after another. The arithmetic is the same, but it makes the ninth slice end on exactly the number where the nakshatra ends, and each slice begin on exactly the number where the one before stopped, so no longitude falls into a gap. The API test suite checks this directly: all 27 nakshatras carry the same nine widths, only rotated, and a sweep of the zodiac in one-arcminute steps finds exactly 243 slices. It also guards the commonest mistake in tables of this kind, starting every nakshatra at Ketu, by asserting that a point early in Krittika returns the Sun.

A worked example with real engine output

The sample birth used across this site's calculator pages is 14 August 1994, 06:42 in Ahmedabad (23.0225 N, 72.5714 E, Indian Standard Time). Run through the engine on 5 October 2026 it returns ten rows and a Lahiri ayanamsa of 23.7779 degrees. Longitudes below are the engine's own, to four decimal places; the page prints every number to two.

Checking the Moon by hand

The Moon is at 204.6401 degrees. Divided by 13.3333 that is 15.35, so it sits in nakshatra number 15 counting from zero: Vishakha, which begins at exactly 200 degrees. The Moon is 4.6401 degrees, or 278.41 arcminutes, into it. Fifteen modulo nine is 6, and the name at position 6 in the cycle, counting Ketu as 0, is Jupiter, so Vishakha's slices open with Jupiter. The running totals are Jupiter 106.67, Saturn 233.33, Mercury 346.67. The Moon's 278.41 lies past 233.33 and short of 346.67, so its sub-lord is Mercury: 45.07 arcminutes into the slice and 68.26 short of Ketu's. Along with the main table the page lists all nine slices of the Moon's nakshatra, so this check can be made on any chart.

What the table shows on a second look

• The Ascendant checks the same way. 122.3301 degrees is 139.81 arcminutes into Magha, which opens with Ketu. Ketu's slice ends at 46.67 and Venus's at 180, so the sub-lord is Venus, 40.19 short of the Sun.
• Rahu shares the Moon's slice. Both stand in Vishakha's Mercury slice, 203.8889 to 205.7778 degrees, so they share a nakshatra lord and a sub-lord. Sharing a slice says the two are within 113.33 arcminutes of each other and nothing more.
• A slice can cross a sign. Vishakha runs from 20 degrees of Libra to 3 degrees 20 minutes of Scorpio, and its Moon slice, 209.4444 to 210.5556 degrees, starts in Libra and ends in Scorpio.
• The cycle skips at a nakshatra's end. The graha Mercury stands in the ninth and last slice of Ashlesha, which is Saturn's. The slice after it is the first of Magha and belongs to Ketu; Ashlesha's own lord, Mercury, is passed over. A Mercury Mahadasha behaves the same way in time: it closes on its Saturn sub-period, and the Ketu Mahadasha that follows opens with Ketu's own.
• Sub-lords are not evenly spread. Four of the ten points here have Mercury and three have Venus. Every lord rules three of the 27 nakshatras, but a sub-lord's share of the zodiac is its years over 120: one position in six falls in a Venus slice and one in twenty in a Sun slice.

Reading each column and each kind of result

The three results the page can return

• Date, time and a place that resolves to real coordinates: ten rows, the Ascendant first.
• Date and time only, or a place that does not resolve to coordinates: nine rows, Moon to Ketu. Given a time and no coordinates the engine could still produce a rising degree for latitude zero; the calculator withholds it, because a sub-lord of that would be a precise-looking figure computed from invented coordinates.
• No time: no result. The Run button stays inactive until a time is entered, and the server separately answers that this calculator needs a birth time. No noon chart is substituted, as it is on date-level pages such as Moon sign.

The columns

• Longitude is sidereal, in degrees from 0 Aries, on the Lahiri ayanamsa. Dividing by 30 gives the sign: 204.64 is 24.64 degrees into the seventh sign, Libra.
• Nakshatra and nakshatra lord are the same values the birth chart calculator gives for the point. For the Moon, that lord is the one that opens the Vimshottari sequence.
• Sub-lord is the lord of the slice the point stands in: one of the same nine names.
• Arcmin to next boundary is the distance from the point forward to the end of its slice. Read this column before the sub-lord.
• Next sub-lord is the lord the point would have if it stood that many arcminutes further on.

The distance is measured forward only

A point that has just entered its slice shows a large distance and still sits close to an edge - the one behind it. To find that side, subtract the distance from the slice's width in the table of widths above. The sample's Mercury is in a Saturn slice, 126.67 wide, with 98.84 to go, so it stands about 32.3 arcminutes past the slice's start. For the Moon the second table prints both edges.

Direction matters too. The Sun, the Moon, a planet in direct motion and the Ascendant all move towards the boundary the row names. A retrograde planet moves the other way, and Rahu and Ketu always do in this engine, which uses the mean node. For those points the boundary being approached is the one behind. The sample shows it: Saturn was retrograde, and across the two hours around the birth its forward distance grew from 56.48 to 56.83 arcminutes, while Rahu's grew from 22.68 to 22.95. This table does not mark retrograde motion; the birth chart calculator does, and the pages on Rahu and Ketu explain the nodes.

One real day, hour by hour and minute by minute

How much does the clock matter for this particular birth? The engine was run across the whole of 14 August 1994 at Ahmedabad, first for the Moon at one-minute steps.

Nine changes in one civil day. The Moon, moving 35.3 arcminutes an hour at the birth time, stood in each of Vishakha's nine slices at some point. The longest full stay was the Venus slice at 3 hours 47 minutes and the shortest the Sun slice at 1 hour 8 minutes. The Mercury slice ran from 05:26 to 08:39, so the recorded time would have to be wrong by 76 minutes in one direction or 117 in the other before the Moon's sub-lord changed. The Ascendant is another matter. Here it is at five-second steps.

The recorded 06:42 falls in the widest slice there is and is still only three minutes from its end: a record reading 06:45 gives the Sun, and one reading 06:34 gives Ketu. Over the whole day the Ascendant's slice changed 244 times. The slower points were not all still either. Mercury changed slice at 01:12, Mars at 23:55 and the Sun at 22:19; Jupiter, Venus, Saturn, Rahu and Ketu kept one sub-lord from midnight to midnight. This is one day. The sub-lord and birth time reports the same measurement over 100,000 random birth moments, and what an unknown birth time costs sets out which parts of a chart survive without a time.

The ayanamsa, and why a few arcminutes matter here

Every longitude in the table is sidereal: the tropical position less the ayanamsa. This engine has one ayanamsa, Lahiri, computed as a straight line from the J2000 epoch. For the sample it is 23.7779 degrees, and the result prints the model's name and its value with the tables.The ayanamsa calculator gives the figure for any date.

A shift of a few arcminutes rarely carries a point across one of 12 sign boundaries or 27 nakshatra boundaries. Here it does so far more often, because the boundaries stand close together: 243 of them in 360 degrees. A different ayanamsa slides every longitude by the same amount, and a point changes sub-lord when a boundary lies within that distance on the side it slides towards. The sample chart happens to be robust. Its nearest boundary ahead is Rahu's at 22.81 arcminutes and its nearest behind is Mercury's at 27.83, so adding up to 22 arcminutes to every longitude, or taking 27 away, changes no sub-lord. The chart this engine's tests use, 15 August 1947 at New Delhi, is the opposite: two of its ten points sit within 3 arcminutes of the boundary ahead. The distance column says which kind of chart yours is.

That is the practical reason this page is not labelled Krishnamurti Paddhati. The only book in this app's library that mentions KP is Advanced Predictive Astrology, chiefly in its publishers' note. The note says the author followed Lahiri, describes the Krishnamurti ayanamsa as very close to it - close enough that Navamsa positions did not change - and says KP readers need planets and cusps with their rasi lord, nakshatra lord and sub lord. A Navamsa division is 200 arcminutes wide. The narrowest slice here is 40 and the average 88.89, so what holds for the Navamsa does not carry over. The note gives no number for the KP ayanamsa, no other text in the library does, and the engine does not guess one. The methodology page states what the astronomy layer is, and why two apps give two different nakshatras follows the same disagreement one level up.

What this page does not compute

• No meaning. The texts this app is built from supply no reading of a sub-lord, so the result is a position, not a prediction. The lords are described on their own pages as grahas - Mercury, for instance - not as sub-lords.
• No house cusps. This app draws whole-sign houses from the rising sign, as the Lagna calculator shows, and computes no cusp longitudes, so there is no cusp to find a sub-lord for.
• No set of 'ruling planets'. Nothing in the library states which lords would belong to such a set or in what order, so none is assembled.
• No level below the sub. BPHS carries the division of time down to the Pratyantardasha, and this engine computes that third level for its timing statements; the Vimshottari Dasha calculator lists the Mahadashas and the Antardashas of the one now running. The arc split here stops after one cut. A further ninefold cut would average 9.88 arcminutes, inside the Moon's own stated error.
• Not the Antardasha at birth. It is tempting to read the Moon's sub-lord as the sub-period running when you were born. In this engine the two do not match, by construction: it subtracts the part of the first Mahadasha that ran before birth and divides the remainder among all nine lords from the birth instant, so the Antardasha it computes for the moment of birth always belongs to the Mahadasha lord. For the sample, the Moon's sub-lord is Mercury and the engine's Antardasha at birth is Jupiter's.
• Not exact positions. The project's method notes give the Moon as accurate to about 0.1 to 0.3 degrees, which is 6 to 18 arcminutes, and the Sun far better. For the five planets they give a check against a VSOP87 ephemeris over 1950-2030: within 0.02 degrees for Mercury, Venus and Mars and 0.16 degrees (about 10 arcminutes) for Jupiter and Saturn. They describe the layer as not a full ephemeris. A row that sits nearer an edge than the error of its position is undecided, whatever the sub-lord column says.

How the slices map onto the first Mahadasha

The one place the arc and the calendar genuinely touch is the Moon's row. Sl. 16 of BPHS Ch. 46 makes the Moon's progress through its nakshatra the measure of how much of the first period has already run. The sample Moon is in Vishakha, so the first period is Jupiter's, 16 years long. Laid along Vishakha's 800 arcminutes, 16 years comes to 7.3 days for each arcminute. The Moon had covered 278.41 arcminutes, which is 5.57 years, leaving 10.43 - and the engine's first Mahadasha for this birth does end on 18 January 2005. What a Mahadasha is explains the balance in full.

Two cautions follow from the same arithmetic. First, the verse speaks of the time the Moon has spent in the nakshatra, while the engine uses the share of arc it has covered. Those are the same only if the Moon keeps a steady speed across the nakshatra, so the engine's balance is an approximation of the verse, not a transcription of it. Second, the Moon's 6 to 18 arcminutes of possible error is 44 to 131 days at Jupiter's rate. The edge of a slice is no sharper than that.

Where this connects in the app

Nothing else in the app reads the sub-lord. In the server code only this calculator calls the function; the Kundali and Timing features are built on the nakshatra lord, the houses and the dasha periods. The page is here for readers who want the slice itself, shown with its margin. The neighbouring pages fill in the rest: the Moon, the rashi and the nakshatra for the level above, the Navamsa for the other fine division that needs a time to the minute, the Moon in Vedic astrology for the graha whose nakshatra starts the dasha count, and the accuracy feature for how the app reports what a missing or rounded birth time costs elsewhere.

Questions

Is this a KP chart?

No. It uses the Lahiri ayanamsa, whole-sign houses and no cusps, and it offers no interpretation. KP uses its own ayanamsa, for which this app's library holds no number, and at this grain a few arcminutes change the answer for points near a boundary. The page computes the Vimshottari proportions along a nakshatra and says exactly that.

Why will it not run on a birth date alone?

Because there would be nothing true to show. On the sample birth date the Moon stood in ten different slices between midnight and midnight and the Ascendant changed slice 244 times. A noon guess would name one of them with false confidence, so the calculator returns no sub-lord at all without a time.

My result has no Ascendant row. Why?

The Ascendant needs real coordinates as well as a time. If the place was left blank, or did not resolve to coordinates, the calculator shows the nine grahas and withholds the Ascendant. It never computes one for latitude zero. Picking your town from the suggestions under the place field is the reliable way to get the row.

My birth time is rounded to the nearest five or ten minutes. Which rows can I use?

Check the distance column against how fast each point moves. At the sample birth the Moon covered about 0.6 arcminutes a minute, so a Moon row survives a rounded time unless it is within a few arcminutes of an edge. The Ascendant covered about 13.5 arcminutes a minute and, in the hour around that birth, stayed in one slice for between 3 and 10 minutes, so its row does not survive rounding.

Another site gives me a different sub-lord. Which is right?

Compare the longitudes first. If the other site uses a different ayanamsa, every longitude differs by the same small amount, and any point nearer a boundary than that amount changes. If the longitudes agree and the sub-lords do not, check that the other table starts each nakshatra from its own lord. The ayanamsa calculator shows the value used here.

What does my sub-lord mean?

This page does not say, because none of the texts the app is built from says. BPHS gives the lords, their years and the proportional rule for periods of time; it does not divide a nakshatra or read a slice. The result is a position with its margin, not a reading.

Why are the slices unequal?

They follow the Vimshottari years in BPHS Ch. 46 Sl. 15. Venus has 20 of the 120 years and so a sixth of every nakshatra, 133.33 arcminutes. The Sun has 6 and so a twentieth, 40 arcminutes. The same proportions size the Antardashas inside any Mahadasha.

Is the Moon's sub-lord my Antardasha at birth?

Not on this site. The engine behind the dasha calculator divides what is left of the first Mahadasha among all nine lords, starting at the birth instant, so the Antardasha it computes for the moment of birth is always the Mahadasha lord's. The sample's Moon has Mercury as sub-lord, and the engine's Antardasha at that birth is Jupiter's.

Does a retrograde planet get a different sub-lord?

No. The sub-lord depends only on the longitude at the birth instant. Retrograde motion changes which boundary the planet is moving towards: the one behind it, not the one the distance column measures. Rahu and Ketu are always in that position here.