Chart basics · Beginner
Coordinated Universal Time
Also called UTC, GMT, Universal Time, UTC
The world's reference clock; a local time plus its offset gives UTC.
Every chart is really calculated for one UTC instant. 10:30 p.m. in New York in June (UTC−4) is 02:30 UTC the next day, which is why a chart's calendar date in UTC can differ from the local one. For astronomy the site then converts to Terrestrial Time.
Sources
Written for Cool Moon Facts in its own words. An astrology source documents what astrologers believe or practise; it does not establish that astrology works.