Lagna Chart (Ascendant / Birth Chart)

What is the Lagna chart?

The Lagna chart — D1, the Rashi chart, or in plain English the birth chart — is a snapshot of the sky from one place at one moment: yours.

Its organising idea is the Lagna itself, the ascendant: the exact point of the zodiac that was climbing over the eastern horizon at the moment you were born. That point fixes the first house. Everything else in the chart is counted from it.

This is why jyotish asks for a birth time and not just a date. The planets move slowly — the Sun takes a month to cross a sign. The horizon does not. The whole zodiac wheels past it every day, so the Lagna advances through all twelve signs in roughly twenty-four hours, about one sign every two hours. Two babies born in the same hospital ninety minutes apart share nearly every planetary position and get different charts.

What the chart is built from

AstroShruti casts the chart from four inputs: your local civil date and time of birth, the timezone of the birthplace, and its latitude and longitude. The local time is resolved to UTC through the birthplace’s own timezone, so historical offsets and daylight-saving rules are handled by the zone database rather than by a hand-entered offset.

Positions come from the Swiss Ephemeris, using its Moshier analytical model — accurate to under an arcsecond for the visible planets, and requiring no external data files. All longitudes in the engine are sidereal: measured against the fixed stars, not the equinox.

The ayanamsha value in degrees at your birth moment is returned with every chart. That is deliberate: it is the single number that explains why this chart differs from a tropical one, and it should not be hidden.

The four chart styles, and what actually differs between them

Nothing in the reading changes with the style. The same sidereal longitudes are drawn four ways, and every regional format is a convention about where a sign or a house sits on the page. What differs is which of the two is nailed down:

The East Indian square (Bengali, Odia and Assamese practice) is the one worth a diagram in words. It is a 3×3 grid with an empty centre, and each of the four corner cells is cut by a diagonal running from the square’s outer corner inward — which turns eight cells into twelve compartments. Meṣa takes the top-centre cell and the rest follow anti-clockwise, so Karka sits at the middle-left, Tulā at the bottom-centre and Makara at the middle-right.

That walk is continuous around the rim: each corner cell is entered along one outer edge and left along the next, which is exactly why its diagonal runs the way it does. Being sign-fixed, it shares the South Indian format’s advantage — the drawing keeps the order of the actual zodiac — and it needs the same thing printed in each compartment: the house number, because the glyph already says which sign a compartment is, and which house that sign became is the part a reader cannot see.

The twelve houses, and how they are counted

Once the ascendant’s longitude is known, its sign becomes the first house, the next sign the second, and so on around the zodiac. A planet’s house is simply how many signs its own sign sits from the Lagna’s sign.

This is the whole-sign method, and it is worth being precise about what it means: a house is a sign here. The whole of Cancer is the first house or none of it is. A planet at 29° of a sign and a planet at 1° of it are in the same house, however far apart they look on the wheel.

A note on the house-system setting

The house-system setting is real and it does change the chart — but less than its name suggests, and you should know exactly where.

AstroShruti supports thirteen house systems, including Placidus, Koch, Equal, Porphyry, Campanus, Regiomontanus and Sripati. In the Lagna chart, the setting feeds the ascendant calculation. The house assignment itself is always whole-sign: houses are counted in whole signs from the Lagna’s sign regardless of which system you select. Selecting Placidus here does not produce Placidus house cusps in the D1 chart.

If you want genuine intermediate cusps — houses that cut across signs, with a planet’s bhava determined by cusp boundaries rather than by its sign — that is the KP system, which computes true Placidus cusps with the KP ayanamsha. Sripati, the classical Vedic bhava-chalit system, is also in the list for that purpose.

We would rather say this plainly than let the dropdown imply something the D1 chart does not do.

What each planet in the chart carries

Every body in the Lagna chart is reported with more than a sign. See Grah Stithi for the full table, but in summary each planet carries its sidereal longitude, its sign and the degrees it has travelled within that sign, its whole-sign house, its nakshatra and pada, the sign lord and nakshatra lord, its full KP star / sub / sub-sub lord chain, and whether it is retrograde.

The Lagna itself gets the same treatment — it is a point on the zodiac like any other, so it has a sign lord, a nakshatra, a pada and a KP chain of its own. The Lagna’s nakshatra and its sub lord are read closely in KP work.

D1 and the divisional charts

D1 is the undivided chart, and it comes first for a reason: every other chart is derived from the same longitudes.

AstroShruti computes the full Shodashvarga — the sixteen classical vargas, from D1 Rashi and D2 Hora through D9 Navamsha, D10 Dashamsha and D60 Shashtiamsha. Each is a rule for re-mapping a longitude into a sign, so the whole set costs one pass of the ephemeris. A varga chart re-arranges the planets; it does not re-observe them.

One consequence worth knowing when you read a varga table: the longitude and the degree-in-sign shown are the D1 values, even in a D9 or D60 chart. Only the sign and the house are re-mapped. That is the intended behaviour — the degree column is there to show you where the planet really is — but it surprises people who expect a “navamsha degree”.

See Divisional charts for how the vargas are read.

Reading order

The chart is a framework, not a verdict. In practice it is read roughly in this order:

1. The Lagna — its sign, its lord, and where that lord sits.
2. The planets by house — see Grah Stithi.
3. Strength — Shadbala and Bhava Bala for which planets can actually deliver, and Ashtakavarga for which signs are supported.
4. Timing — Vimshottari dasha for when, and Gochar for what is passing over it now.
5. The birth panchang — the almanac of the day you were born on.

Notes on this chart

• Longitudes are sidereal, Lahiri by default, from the Swiss Ephemeris (Moshier model).
• Houses are whole-sign from the Lagna’s sign, in every varga.
• Rahu and Ketu are the lunar nodes — Ketu is always exactly 180° from Rahu, and both are always shown retrograde.
• The ayanamsha in degrees at the birth moment is shown with the chart.