Setting Circles are used on telescopes to find astronomical objects in the sky by their coordinates as listed in a star chart or ephemeris using the celestial coordinate system. 50 cm refracting telescope at Nice Observatory. ... A star chart is a map of the night sky. ... An ephemeris (plural: ephemerides) (from the Greek word ephemeros= daily) was, traditionally, a table providing the positions (given in a Cartesian coordinate system, or in right ascension and declination or, for astrologers, in longitude along the zodiacal ecliptic), of the Sun, the Moon, the planets, asteroids or comets in the... In astronomy, a celestial coordinate system is a coordinate system for mapping positions in the sky. ...

Setting Circles on a equatorial fork mounted telescope

An Equatorial Mount for a telescope. ... 50 cm refracting telescope at Nice Observatory. ...

Description

Setting Circles consist of two graduated disks attached to the right ascension (RA) and declination (DEC) axis of an Equatorial mount. The right ascension disk is graduated into hours, minutes, and seconds. The declination disk is graduated into degrees, minutes, and seconds. Since right ascension coordinates are fixed to the celestial sphere the RA disk is usually driven by a clock mechanism in sync with sidereal time. Locating an object on the celestial sphere with settings circles is similar to finding a location on a terrestrial map using latitude and longitude. Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... An Equatorial Mount for a telescope. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy and navigation, the celestial sphere is an imaginary rotating sphere of gigantic radius, concentric with the Earth. ... Sidereal time is time measured by the apparent diurnal motion of the vernal equinox, which is very close to, but not identical with, the motion of stars. ... In astronomy and navigation, the celestial sphere is an imaginary rotating sphere of gigantic radius, concentric with the Earth. ... Latitude, usually denoted symbolically by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ... Longitude, sometimes denoted by the Greek letter λ, describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. ...