Ra

(astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours and minutes and seconds; used with declination to specify positions on the celestial sphere

（天文学）春分点から天球上の天体を通る時圏との交点まで天の赤道に沿って東向きに測った角度を指定する赤道座標；通常は時・分・秒で表される；天球上の位置を指定するために赤緯とともに用いられる