Methodology

The positions of the Sun, Moon and planets are taken from JPL ephemerides — numerical tables of Solar System bodies' motion published by NASA's Jet Propulsion Laboratory.

Longitudes are calculated as apparent geocentric ecliptic for the epoch date — these are used in astrology. The ecliptic inclination is taken as true: the mean value corrected for nutation.

Outer planets are taken as the barycentres of their systems: they have no central body of their own. The contribution of this approximation is hundredths of an arcsecond, i.e., less than any practically significant magnitude for a chart.

Local birth time is converted to UTC using the historical time zone of the location – via the IANA database, which records the offset in effect on a specific date at a specific place.

Historical accounting is mandatory. Example from platform checks: Moscow, 12 April 1991. In spring 1991 decree time was abolished and daylight saving introduced simultaneously, so the correct offset here is UTC+3, not the usual UTC+4 for April. Assuming “Moscow in April – plus four” yields a chart shifted by one hour, along with the Ascendant and all houses.

Therefore the birth city is selected from a directory rather than typed manually: the platform needs coordinates and zone, not the name.

The birth moment is converted to UTC, planetary positions are taken from the ephemerides for that moment, then they are transformed into ecliptic coordinates for the date’s epoch and placed into the signs.

The threshold below which a discrepancy is considered unacceptable is one arcminute compared with JPL Horizons calculations. One minute was chosen deliberately: it is roughly the precision at which a planet can no longer mistakenly fall into an adjacent sign or house.

The set of objects is fixed: Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto and calculated points – Ascendant, Midheaven, lunar nodes, Lilith. Chiron and asteroids require separate data cores and are not shown until they are integrated: the platform has no placeholders or approximate values.

The primary system is Placidus. The Ascendant and Midheaven are calculated from sidereal time, true ecliptic inclination and the location's latitude; intermediate cusps are derived iteratively, as points on the ecliptic that have passed a given fraction of its semi‑arc.

The method has a precise applicability limit — about 66.56° latitude. Above this, the daytime arc degenerates: the point becomes non‑rising or non‑setting, and Placidus ceases to be meaningful. Beyond this limit the calculation switches to Porphyry and indicates which system is used.

Without a known birth time, houses are not constructed at all. The Ascendant completes a full circle in a day, moving one degree every four minutes: substituting noon would produce a plausible but not your chart.

An aspect is the angle between two bodies that falls within the allowed deviation from the exact value. The deviation is called an orb; the platform's orbs are listed in the table under the sections.

An aspect is considered convergent if, after 0.2 days, the discrepancy with the exact angle decreases. For the Moon in transits, the orb is limited to three degrees: with a full orb it produces noise that masks significant events.

Transit – the aspect of a planet currently moving to a point in your chart. The platform scans the selected time interval, calculates angles and records moments when the angle falls within the orb.

For each occurrence the date, participants and whether the aspect is applying or separating are saved. From these occurrences the day chart, weekly, monthly and yearly forecasts are compiled: this is a single calculation with different windows, not four separate predictions.

The meaning of a planet, sign, house and aspect is a written text, not a model’s improvisation. It is the same for everyone and does not depend on who opened the page.

What becomes personal is not the interpretation itself but its selection: from the general descriptions those relevant to your geometry are taken and linked into a text. Hence the knowledge base can be read separately from the chart – it is the same material.

The language model receives already calculated numbers and explains them. It has no access to the calculation and cannot insert its own degrees: all it sees is ready-made geometry and written interpretations.

Each model call is logged: model, purpose, token count, cost and duration. The tariff limits are based on this record.

Planet positions – via JPL Horizons, NASA’s open service. Set the date and time in UTC, choose geocentric ecliptic coordinates and compare the longitudes with those shown by the chart.

Time zone – according to the IANA database: it is public, you can view the offset history for your city there.

Ascendant – at the moment of the Sun’s geocentric rise its longitude must match the Sun’s longitude. This is an external check: it catches errors in the ecliptic tilt, sidereal time, and the Ascendant formula simultaneously.