What is calculated—and what is not

One clear astronomical convention

The calculator locates 2060 Chiron using apparent geocentric ecliptic longitude referred to the equinox of date. It uses the tropical zodiac: twelve equal 30° sections starting at 0° Aries. These signs are not identical to the astronomical constellation boundaries.

The browser engine is Caelus 0.24.1. Its Chiron fit is documented as derived from JPL Horizons. Position calculations and symbolic astrological interpretations are separate: computing an object’s position does not establish that an interpretation is scientifically predictive.

A missing birth time is a range, not noon

Unknown time covers the whole local birth date. Approximate time means the selected number of local-clock minutes before and after the time entered. Exact means the clock time you entered; it does not certify the accuracy of the original record.

When a timezone is known, all applicable historical offset segments are considered. Clock gaps are not shifted automatically. A repeated clock time can retain both UTC possibilities until you select the earlier or later occurrence. A completely skipped civil date is rejected.

Without a timezone, a conservative envelope uses the minimum and maximum offsets present in the pinned timezone dataset over the supported date range. It is intentionally broader than using your current browser timezone.

Precision and boundaries

The internal model range is 1900–2099; the birthday form accepts dates from 1900 through today using the UTC calendar. Internal evaluation includes padding beyond the selected date for timezone uncertainty.

Intervals are checked at steps of no more than 15 minutes. Each cell includes a 0.005° position allowance plus a conservative 2°/day speed-envelope allowance between samples. These are engineering safeguards with reference tests, not a formal interval-arithmetic certification or a probability distribution.

If an envelope reaches a sign boundary, more than one sign is shown. Exact displayed positions stop at the whole arcminute without rounding into the next sign. Possible ranges may be wider than the nominal astronomical motion because they include the guard margin.

Motion is tested separately. A speed interval touching ±0.001°/day, including its numerical and between-sample allowances, is labeled near station / changing. It is not forced into direct or retrograde.

Houses need a different level of detail

House calculation requires an exact, unambiguous time, coordinates and a recognized timezone. Unknown or approximate times do not receive an invented house.

Placidus is the default. Whole Sign is available only when explicitly selected. If the engine cannot calculate the requested system at a polar latitude, the site withholds the house rather than labeling an automatic replacement as Placidus.

House membership follows the Chiron ecliptic longitude between house cusps. Within 0.025° of a cusp, a single house is not asserted. These numerical margins are not guarantees about the accuracy of your recorded birth time or location.

City locations use city centers. Close to a cusp, a small change in time or coordinates may matter. Manual coordinates and timezone entries are recorded as user-supplied, not independently verified.

Historical places and timezones

City data is derived from the GeoNames cities15000 dataset, partitioned by country for local search. It is not a complete list of every town or historical locality. Manual coordinates and timezone entry remain available.

Historical conversion uses the timezone database shipped with the pinned moment-timezone package. The precise data version is displayed with each result. Historical records, particularly before 1970, can be incomplete. Old birth records may use conventions the database cannot reconstruct.

Interpreting the result

The short readings are original symbolic reflection prompts. They do not diagnose trauma or illness, infer personal events, promise healing, or predict relationships and career outcomes. Your lived experience takes priority over a chart description.

Different results elsewhere can come from a different timezone, zodiac, house system, birth-time assumption, coordinate choice or numerical model. Compare the settings first.