Attribution and methodology

Data sources

Tianji uses deterministic location and time data for chart calculations. AI is not allowed to guess coordinates or time zones.

Global place data

Place names, coordinates, administrative names, population data, and IANA time zone identifiers are derived from GeoNames, licensed under CC BY 4.0. GeoNames data is provided without warranty.

True solar time

The service combines the selected longitude, the location's historical UTC offset for the entered date, and the equation of time. Daylight-saving rules are resolved from the IANA time zone database available to the server runtime.

User verification

Users can review the selected city, country, coordinates, time zone, clock correction, and resulting solar time before generating a report.