Sidera Chart’s Eight Astrology Calculators

Field notes

The site standardizes its calculators around three inputs: civil birth date, birth time, and birthplace, with an unknown-time option that omits houses while retaining planetary calculations. Its technical notes specify astronomy-engine with VSOP87 and lunar theory, tropical zodiac, Placidus houses, and separate aspect orbs. Relationship charts are handled distinctly: synastry compares two charts, while composite uses shorter-arc planetary midpoints.