Zodiac rising sign calculator

The ascendant is the ecliptic degree on the eastern horizon at your birth instant, from local sidereal time, the obliquity, and your latitude. A few minutes of clock can change it, so the margin panel tells you how much slack you have. The tool follows the chosen IANA zone's own rules for the birth date, including daylight saving where it applied; it does not guess local mean time for places or years outside the zone tables. The sidereal option uses an approximate Lahiri ayanamsa, good to about an arc minute.