Methodology and calculation choices
Merolot calculates planetary positions with an astronomical calculation engine, using the tropical zodiac and the Placidus house system. The calculation is deterministic: the same birth data always returns the same result. Interpretive text is written on top of that calculated table and passes editorial review before publication.
THE CALCULATION STACK
| LAYER | CHOICE | WHY |
|---|---|---|
| Ephemeris | Astronomical position calculation | Positions are computed from a sky model rather than read from a stored table. |
| Zodiac | Tropical | The standard of the Western tradition; it is anchored to the spring equinox and the cycle of the seasons. |
| House system | Placidus | The most widely used quadrant system in modern Western astrology, and the default of most US chart services. |
| Lunar nodes | Mean node | The true node oscillates; the mean node keeps results comparable between sources. |
| Lilith | Mean Lilith | The common form; every page that shows Lilith names which one it used. |
| Time and place | UTC canonical · IANA time zone | Birth time is resolved with the historical time zone of the birthplace, daylight saving rules included. |
THE ENGINE CALCULATES, THE AI NARRATES
This is the clearest line Merolot draws: every number on a page is the output of a calculation, and every sentence is the narration of that calculation. The two do not come from the same place.
The language model does not guess at the sky. The calculated table is placed in front of it — which planet in which sign, at what degree, in what aspect — and the model narrates that. This is why a reading cannot get a date, a planetary position or a retrograde status wrong: those values come from the engine, not from the text.
- Planet, moon and node positions — sign, degree, retrograde status
- House cusps and the rising sign
- Aspects and orb calculations
- Moon phases, void-of-course windows, planetary hours
- Rule-based scores such as compatibility percentages
- Turning the calculated table into everyday language
- Setting the section headings and the reading order
- Keeping the tone calm and free of overstatement
HOW INTERPRETATIONS ARE PRODUCED
Every interpretive text passes through the same four steps. The chain is fixed; skipping a step means the content is not published.
- 1 · Calculation
- Sky data is taken from the engine. Date, place and time zone are fixed at this step, and no later step can change that data.
- 2 · Template
- Each content type has a fixed template: which sections, in which order, at what length. Templates are versioned, so the shape of the output cannot change without a version change.
- 3 · Generation
- The template and the calculated data are given to a language model. The model is pinned and recorded: which text came from which model and template version stays traceable.
- 4 · Editorial review
- Before publication the text is checked for accuracy, tone and boundary rules. Text that is not approved is not published; where data is missing the section is hidden rather than filled in.
WHY DOES EVERY SITE SHOW A DIFFERENT RISING SIGN?
Two sites can return different results for the same birth data for three common reasons, and none of them is a calculation error.
The first is the house system. Placidus, Koch, Equal House and Whole Sign place the intermediate cusps at different degrees. The four angles — the 1st, 4th, 7th and 10th cusps — agree across all quadrant systems; the gap widens in the houses between them. Whole Sign is the exception: it makes the whole rising sign the 1st house, so a chart can move a planet a full house.
The second is the time zone. Which zone and which daylight saving rule a birth time is resolved with can shift the rising sign by an entire sign. Merolot uses the historical time zone of the birthplace, not the current one.
The third is the choice of ephemeris and points: mean node or true node, mean Lilith or another calculation. These are preferences rather than errors, and naming which one is in use is the minimum standard of honesty.
WHY PLACIDUS, AND WHAT WHOLE SIGN CHANGES
Merolot calculates houses with Placidus. The reason is compatibility rather than doctrine: Placidus is the default of most English-language chart services, so a reader comparing a Merolot chart with a chart calculated elsewhere is comparing the same house layout instead of debugging a mismatch.
Placidus is a time-based quadrant system: it divides the arc each degree of the ecliptic takes to rise, which is why house sizes vary with latitude and why houses become distorted at extreme latitudes. Above roughly 66 degrees the system breaks down, and any Placidus chart from the far north or far south should be read with that limit in mind.
Whole Sign is the main alternative and it is not a rounding of Placidus. It makes the entire rising sign the 1st house, the next sign the 2nd, and so on, so cusps and sign boundaries coincide. Under Whole Sign a planet near a Placidus cusp regularly lands in a different house, which is the single most common reason two charts disagree about where a planet sits.
Neither system is more correct than the other; they answer slightly different questions and the Hellenistic tradition used Whole Sign for centuries. Merolot states its choice rather than presenting one convention as the truth. Where a page depends on the house system, it says so.
SOURCES AND TRADITION
The interpretive frame rests on the Western astrological tradition: the house and aspect structure that took shape in the Hellenistic period, carried in the language of modern psychological astrology.
Planetary rulerships are given in both the traditional and the modern form — Scorpio's traditional ruler is Mars and its modern ruler is Pluto, for example. Pages show both and say which tradition each belongs to.
Astronomical data is produced by the calculation engine. What is astronomical and what is interpretive are kept apart on the page: a position and a degree are measurable facts, while meaning is a proposal of the interpretive tradition.
CREDITS
Merolot is an independent publishing project for astrology and tarot content. The material is produced by its own sky-calculation engine and an editorial flow that reviews every text before it is published.
No fictional astrologer byline is used. Where interpretations are produced with AI assistance and reviewed editorially, the page says so.
Publisher: Merolot. Electronic contact for every request, question and correction report: [email protected]. The same details are stated in the privacy policy and the terms of use, so the three pages carry one consistent record.
CORRECTION POLICY
A calculation error outranks a content error: if a planetary position, a house cusp or a date is wrong, the record is corrected and every affected page is regenerated.
When an error in interpretive text is corrected the page's update date changes; no page is edited silently after the fact.
Errors are reported to [email protected]. Naming the page address and the line you believe is wrong lets the record be verified quickly.
This page is a declaration rather than a showcase: it states which systems are used, what is calculated, and what is interpreted — each one separately.