We'd like to use analytics cookies to understand which symbols people look up, so we know what to research next. They are not used for advertising and we set none of them unless you say yes. What we store.
A clock keyed to the stars rather than to the sun.
Also known as: Local sidereal time, Star time
Sidereal time runs about four minutes a day faster than solar time, because a day measured against the stars is shorter than one measured against the sun. An observatory keeps it because the right ascension of an object crossing the meridian equals the local sidereal time.
Measures time by the apparent rotation of the stars rather than of the sun, running about four minutes a day ahead of solar time.
Contexts: Technical drawing, Maps
Equals the right ascension of whatever is crossing the observer's meridian, which is why observatories keep it.
Contexts: Technical drawing, Maps
A time in numerals shown on a circular clock face with hands, kept alongside an ordinary clock in an observatory.