Engine and horizon model
Calculations use Astronomy Engine 2.1.19. Solar and lunar rise/set searches include the apparent upper limb and standard atmospheric refraction. Twilight uses geometric solar-center altitudes of −6, −12 and −18 degrees. The site assumes an unobstructed sea-level horizon at 0 metres elevation.
Local civil-date boundaries
The IANA time zone defines the beginning and end of each local date. Only events inside that interval are shown. This handles daylight-saving transitions and prevents a Moon event from a different UTC day being labelled as today’s local event.
Coordinate provenance and limitations
Original IANA representative locations and Korean regional records retain their route identities. Additional city coordinates come from GeoNames. The source is named on each city page. City reference points are not exact observing-site coordinates; refraction, elevation and terrain affect real-world visibility.
Dated HTML and interactive results
The initial HTML contains an explicitly dated reference table. With JavaScript available, the page calculates the selected date, or today in the selected city. A shared link retains its date. The minute display does not imply zero uncertainty, and this independent tool does not replace an official almanac.
Source attribution
GeoNames · CC BY 4.0. IANA timezone reference points and existing Korean regional coordinates are retained. Added place records are from the GeoNames cities15000 dataset retrieved 2026-10-07. Astronomy Engine 2.1.19 is MIT licensed.
The initial HTML table is explicitly dated. JavaScript computes the visitor-selected date or today in the selected city.