Once you’ve identified the planetary coordinates, you can move on to constructing the stellar horoscope, also known as the Vedic or Indian birth chart.

While the position of the planets in the zodiac signs reflects the psychological portrait and karma of a person, their position in the astrological houses reveals how that karma will manifest in different areas of life.

Step One: Determine the Ascendant (Lagna)

The construction of a Vedic chart begins with calculating the Ascendant — the sign of the zodiac that was rising on the eastern horizon at the exact moment of birth — and the precise degree of ascension.

Required Data:

To calculate this accurately, you’ll need:

The true planetary positions

The geographic latitude and longitude of the birthplace

A house table reference such as Placidus or Koch Greenwich Mean Time of birth

To calculate the Placidus Time (Tpl), use this formula:

Tpl = Sidereal Time + Tc − N − 1 + D / 15 (in degrees/hour)

Where:

Sidereal Time is the sidereal hour at the moment of birth.

You’ll find this in the first column of the ephemeris — it lists the sidereal time at 0:00 GMT for each calendar day.

To refine the Sidereal Time for your exact birth time:

Take the difference between the sidereal time of your birth day and the next day. Divide that difference by 24 hours. Multiply the result by your exact birth time in Greenwich Mean Time (GMT). Add that value to the earlier Sidereal Time listed in the ephemeris.

Example:

(1 hr 5 min 56 sec – 1 hr 2 min 00 sec) ÷ 24 hrs × 15 hrs + 1 hr 2 min =

≈ 1 hr 4 min

✅ Example:

Let’s say:

Sidereal Time on Day 1 = 1 hr 2 min

Sidereal Time on Day 2 = 1 hr 5 min 56 sec

Your GMT birth time = 15 hours (3 PM)

Then:

(1h 5m 56s − 1h 2m 0s) = 3m 56s  

3m 56s ÷ 24h × 15h = ~2m 28s  

Add to 1h 2m = Final Sidereal Time ≈ 1h 4m 30s

Tc is your birth time in GMT N − 1 is a standard correction constant used in Placidus charts D is the longitude of your birth location

The result gives you Tpl in degrees/hour

Once you have Tpl, you can look up the Ascendant (Lagna) for that time using the Placidus or Koch tables and finalise the full layout of the chart.

📌 Note: Daylight Saving Time Adjustment

If a person was born during Daylight Saving Time, you must subtract one additional hour from the local time (Tc) in the formula.

Let’s plug in all the values into the formula:

Tpl = 1 hour 4 minutes + 15 hours + (30′ 25″ ÷ 15°/hour)  

Tpl = 15 hours 6 minutes

🔎 Using the “Tables of Houses”

Now that you’ve calculated Tpl, use the Tables of Houses to find the Ascendant degree (the degree rising at the eastern horizon).

In the reference book, Tpl is listed in the left-hand column. The rows show the latitude of the place of birth. You’ll only need one column: “Asc” (Ascendant).

If your Tpl doesn’t exactly match any value in the tables, use interpolation to estimate it between two values.

Example:

If you’re interpolating between:

4°22′20″ and 8°42′30″ Then:

(8°42′30″ – 4°22′20″) ÷ 2 = 6°32′25″ Aries ♈️

✨ Final Step: Subtract the Ayanamsa

The Ayanamsa is the difference between the tropical (Western) and sidereal (Vedic) zodiacs.

To get the sidereal ascendant (Lagna), subtract the Ayanamsa from the tropical Ascendant:

6°32′25″ Aries – 23°29′43″ = 13°2′42″ Pisces

🔮 Building the Stellar Horoscope

The sign containing the Lagna (Ascendant) becomes the 1st house of the chart.

In this case:

1st house: Pisces 2nd house: Aries 3rd house: Taurus, and so on in zodiac order.

🧘 Equal House System in Vedic Astrology

Vedic astrology uses an equal house system popularised by Sage Parashara, where:

The entire sign that contains the Lagna becomes the 1st house. It doesn’t matter if the Ascendant is at 1° or 29° — the whole sign is treated as one house.

This makes the chart much easier to read and is still the standard for most classical Vedic astrologers.

There is also another method where houses are fixed at 30 degrees each, starting exactly at the Ascendant degree, but in this course we will follow Parashara’s system.