An exact transit calendar answers “when does this aspect perfect?” An intensity timeline answers a different question: “when do several slow contacts occupy the same part of a multi-year span?” The graph preserves the individual moving planets while adding their daily contributions into one overview.
Start with one fixed natal chart
The recorded local birth time is converted to UTC with the offset entered by the reader. The calculator then finds apparent geocentric tropical longitudes for the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Birth coordinates establish the Ascendant and Midheaven. The instantaneous lunar orbit supplies the true North Node. These thirteen natal points remain fixed through the timeline.
A wrong civil offset changes the birth instant. A rounded birth time can move the Moon, Ascendant, and Midheaven enough to alter their contact dates. The graph therefore requires a time and place instead of inventing noon or omitting the angles without notice.
Sample the moving planets once per UTC day
For every date in the selected interval, Jupiter through Pluto are calculated at 12:00 UTC. A five-year run normally contains 1,826 or 1,827 samples depending on leap days. A start on 29 February uses 28 February as its later anniversary when the ending year is not a leap year. Each moving longitude is compared with every fixed natal point at conjunction, sextile, square, trine, and opposition.
The angular error is the distance from the ideal aspect. A Saturn–Sun separation of 89.40° has a 0.60° error from a square. A separation of 90.75° has a 0.75° error. Direction around the zodiac does not change this proximity score.
daily contribution = closeness × aspect weight × natal-target weight
combined index = sum of every active daily contribution
The declared weights
| Factor | Weight | Reason in this model |
|---|---|---|
| Conjunction or opposition | 1.25 | Raises the two axial aspect families above the other contacts. |
| Square | 1.00 | Sets the middle reference value. |
| Trine or sextile | 0.75 | Keeps these aspects visible with a smaller peak contribution. |
| Natal Sun–Mars, Ascendant, MC | 1.00 | Full target contribution. |
| Natal Jupiter–Pluto or true North Node | 0.60 | Reduces the many slow-to-slow overlaps that can otherwise dominate a long graph. |
The moving planet itself has no fixed height multiplier. Its speed appears through duration: a slow passage remains inside the one-degree window for more consecutive daily samples.
A worked daily score
Suppose transiting Saturn is 89.40° from natal Sun. The square is 0.60° from exact, so closeness is 0.40. The square weight and Sun target weight are both 1.00, giving a contribution of 0.40.
On the same date, suppose transiting Neptune is 0.25° from a conjunction with natal Uranus. Closeness is 0.75. Conjunction has weight 1.25, while an outer natal target has weight 0.60. That contact contributes 0.75 × 1.25 × 0.60 = 0.5625. If no other contacts are active, the combined daily index is 0.9625. The Saturn and Neptune curves retain their separate values, while the dark total curve shows their overlap.
Why a slow contact becomes a wide curve
A planet moving 0.10° per day can take about twenty days to cross a two-degree-wide window from one-degree applying to one-degree separating. Near an apparent station, it can remain there much longer. Daily linear proximity points therefore form a rounded or stepped triangle rather than a single spike. Retrograde reversal can keep one window open, split it after a brief exit, or produce later returns to the same aspect.
This calculator reports sampled windows. The first row is the first noon sample inside one degree; the final row is the last. It does not imply that the true boundary crossing happened at noon. The listed closest sample is likewise the nearest daily observation, rather than a root-solved exact time.
How the peak table is selected
Every local maximum of the combined daily index is a candidate. Candidates are ranked by height, and the tool keeps no more than one inside each 21-day neighborhood. It then restores chronological order for reading. This avoids filling the table with consecutive dates from one broad slow transit. The longest-window table is independent: it ranks single planet–aspect–target sequences by the number of daily samples inside the orb.
How this model differs from other intensity charts
WitchcraftDaily timeline defines its weights above, uses one noon sample per day, gives slow motion width rather than an additional speed-based peak multiplier, and exposes daily CSV rows. Its calculations use the site’s bundled Astronomy Engine and original renderer.
Range, exports, and practical limits
The supported calendar is 1800–2100, and the whole selected interval must fit inside it. The SVG preserves the visible curves as a scalable local file. The CSV contains every daily date, total, individual planet scores, and the strongest active contact. These files describe the result under the displayed settings; they do not add exact contact times.
Other software can disagree because of ephemeris, coordinate frame, node method, birth data, orb, aspect selection, sampling clock, or weights. Chiron and asteroids are omitted. The one-degree orb is a model setting. Astrological use is symbolic, and the plotted index is not evidence of cause, risk, diagnosis, or a guaranteed event.