Brief introduction to the concepts of right ascension and declination

1. Right ascension is one of the coordinate values used by astronomy in celestial equatorial coordinate system. It passes through the celestial pole, perpendicular to the celestial equator, and the other coordinate value is declination.

2. Right ascension is similar to the angular distance of the longitude of the earth. Used with declination to determine the position of celestial bodies in the celestial sphere. Calculated eastward along the celestial equator from the vernal equinox. The declination similar to the latitude of the earth refers to the distance from the celestial body to the north and south poles of the celestial equator. Right ascension is a coordinate of celestial equatorial coordinate system. Refers to the arc segment on the celestial equator between the right ascension circle passing through vernal equinox and the right ascension circle passing through celestial bodies, which is denoted by α. From the vernal equinox, it is measured in the opposite direction of the apparent motion of the celestial sphere on Sunday, from 0h to 24 h.

3. The declination is similar to the latitude on the earth, and it is the projection of latitude on the celestial sphere. The unit of declination is degrees, the smaller units are "angular minutes" and "angular seconds", the celestial equator is 0 degrees, the declination number in the northern hemisphere is positive, and that in the southern hemisphere is negative. The North Pole is +90 and the South Pole is -90. It is worth noting that the plus sign must also be marked. For example, Vega's exact declination (October 2000) is +38 470 1. The declination of the observer's zenith is the same as that of the observation point.