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sagitta
Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for "arrow", and it should not be confused with the larger constellation Sagittarius, the archer. Although Sagitta is an ancient constellation, it has no star brighter than 3rd magnitude and has the third-smallest area of all constellations (only Equuleus and Crux are smaller). It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. Located to the north of the equator, Sagitta can be seen from every location on Earth except within the Antarctic circle.
The red giant Gamma Sagittae is the constellation's brightest star, with an apparent magnitude of 3.47. Two star systems have been found to have planets.
== Characteristics ==
Covering 79.9 square degrees and hence 0.194% of the sky, Sagitta ranks 86th of the 88 modern constellations by area.〔 Its position in the Northern Celestial Hemisphere means that the whole constellation is visible to observers north of 69°S. It is bordered by Vulpecula to the north, Hercules to the west, Aquila to the south, and Delphinus to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'Sge'. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of twelve segments (''illustrated in infobox''). In the equatorial coordinate system, the right ascension coordinates of these borders lie between and , while the declination coordinates are between 16.08° and 21.64°.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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