A natal chart calculation converts a birth date, time and location into the positions of celestial bodies and local chart angles for that moment. Software such as Swiss Ephemeris handles the astronomical calculations; an astrologer then interprets the resulting positions.
1. Birth date and clock time
The recorded local birth time has to be interpreted in the correct historical time zone, including daylight-saving rules where relevant. An error here can shift chart angles and houses.
2. Geographic location
Latitude and longitude define the observer's position on Earth. They are required for the local horizon, Ascendant, Midheaven and house calculations.
3. Convert to the astronomical time basis
The calculation engine converts the local civil input into the appropriate universal and astronomical time values used internally for ephemeris computation.
4. Calculate planetary positions
The Sun, Moon and planets are placed by longitude in the zodiac. Additional data can include latitude, speed, retrograde status and other coordinate choices.
5. Calculate Ascendant and Midheaven
These are local angles, not planets. They depend strongly on time and place. This is why a guessed birth time can produce a chart that looks precise but has unreliable structural anchors.
6. Choose a house system
Placidus, Whole Sign and other systems divide the chart differently. The planets themselves do not move in the sky when you switch systems; their house labels can change because the house boundaries change.
7. Calculate aspects
Aspects are angular relationships between points in the chart, such as conjunctions, oppositions, trines and squares. The exact angles are mathematical; the meanings assigned to them are interpretive.
8. Add the Ava Lux Kabbalistic layer
Only after the birth chart is established does Ava Lux add the Hebrew-calendar conversion, month-letter correspondence, Tikkun framework, Tree of Life and other symbolic structures. Keeping this order prevents mystical interpretation from contaminating the basic calculation.
Sources and textual boundary
Ava Lux editorial rule: source texts, later Kabbalistic interpretation, modern astrology and the Ava Lux reading method are not treated as if they were the same layer. Where traditions disagree or textual versions vary, the page says so.