Professional-Precision Synastry Calculation
Numji's synastry calculation infrastructure was compared against reference astronomical data and independent geometric controls across 250 couple test cases generated from diverse dates, times, and locations. A total of 67,709 results were examined for the two charts' planets, houses, axes, reciprocal house placements, and interchart aspects.
Birth charts of both individuals, reciprocal house placements, interchart aspect types, and orb values passed the established acceptance criteria across all cases within the test scope. Five results were separately reviewed as they were extremely close to the natural limits of the calculation; no failed results were found.
Validated synastry calculations
The primary result groups covering the individual accuracy of both charts and their geometric relationship.
TWO BIRTH CHARTS
Both individuals' planetary longitudes, motion directions, ASC–MC values, and twelve house cusps were separately checked.
INTERCHART ASPECTS
Aspect types, true angles, and orb values formed between points in one chart and points in the other chart were independently recalculated.
RECIPROCAL HOUSE PLACEMENTS
Placements of Person A's points in Person B's houses and Person B's points in Person A's houses were compared.
LAYER AND SYMMETRY CONTROL
The synastry layer was independently regenerated; it was validated that swapping the order of the individuals preserves the mathematical integrity of the relationship.
Validation results
Numerical distribution of the tested calculation groups. Boundary cases were evaluated separately and are not classified as failures.
| Calculation Group | Comparison | Compatible | Boundary Review | Result |
|---|---|---|---|---|
| Chart A: ASC and MC | 500 | 500 | 0 | Passed |
| Chart A: house cusps | 3,000 | 3,000 | 0 | Passed |
| Chart A: planetary positions | 4,250 | 4,250 | 0 | Passed |
| Chart A: motion directions | 4,250 | 4,249 | 1 | Passed |
| Chart B: ASC and MC | 500 | 500 | 0 | Passed |
| Chart B: house cusps | 3,000 | 3,000 | 0 | Passed |
| Chart B: planetary positions | 4,250 | 4,250 | 0 | Passed |
| Chart B: motion directions | 4,250 | 4,250 | 0 | Passed |
| Aspect membership boundary checks | 2 | 0 | 2 | Reviewed |
| Interchart aspect types | 11,569 | 11,569 | 0 | Passed |
| Interchart true angle | 11,569 | 11,569 | 0 | Passed |
| Interchart orb values | 11,569 | 11,569 | 0 | Passed |
| Reciprocal house placements | 8,500 | 8,498 | 2 | Passed |
| A–B order swap control | 250 | 250 | 0 | Passed |
| Independent synastry layer | 250 | 250 | 0 | Passed |
| Total | 67,709 | 67,704 | 5 | Passed |
Highlighted precision results
Comparison of observed differences for interchart geometry against acceptance criteria.
| Measurement | Average Difference | Maximum Difference | Evaluation | Result |
|---|---|---|---|---|
| Interchart true angle | 0.004114° | 0.032586° | Within professional acceptance limit | Passed |
| Interchart orb value | 0.004112° | 0.032586° | Within professional acceptance limit | Passed |
| Chiron longitudes | 0.00000065° | 0.00000354° | Within 0.03° acceptance limit | Passed |
| Aspect type boundaries | — | 2 boundary cases | Extremely close to orb threshold | Reviewed |
| House cusp boundaries | — | 2 boundary cases | Extremely close to house line | Reviewed |
| Motion direction boundary | — | 1 boundary case | Extremely close to station moment | Reviewed |
Why do boundary cases occur?
When an astronomical value is extremely close to a classification line, very small numerical differences can produce a different label.
HOUSE LINE
Two placements remained right next to a house cusp. While the point's longitude was consistent, which side of the line it was counted on created a different house label.
ORB THRESHOLD
Two aspects were located right next to the orb boundary used. A very minor geometric difference affected whether the aspect was included.
STATION MOMENT
One Mercury result was very close to its turning point. Both measurements showed the motion was practically stationary.
Test methodology
The goal was to ensure that results rely on varied chart structures and independent repeat controls rather than a single couple sample.
SCOPE
- 250 distinct couple cases
- Separate astronomical controls for two charts
- Total of 67,709 comparisons
- Failing test cases: 0
INDEPENDENT CONTROLS
- Comparison with reference astronomical data
- Geometric recalculation of aspects
- Independent regeneration of the synastry layer
- Symmetry check on A–B order swap
CHIRON VALIDATION
A total of 1,000 Chiron results, including longitudes and motion directions across both charts, were directly compared against reference values. All results were found to be compatible, with a maximum longitude difference measured at 0.00000354°.
INDEPENDENT CALCULATION
Reference sources were used strictly for comparison purposes. Numji's production calculations are executed within its own calculation infrastructure independently of the validation tool.
What does this result mean for the astrologer?
The two natal charts, reciprocal house placements, and interchart aspects upon which synastry interpretation relies are delivered with a calculation infrastructure backed by an extensive numerical validation set. This allows astrologers to focus on holistically evaluating the symbolic dynamics of the relationship rather than technical computations.