Sh 2-21

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Sharpless 2-21

Emission nebula
H II region
As seen by the legacy survey
Observation data: J2000 epoch
Right ascension	17h 51m 42s
Declination	−28° 54′ 00″[1]
Distance	26100 ly   (7600 pc)
Apparent magnitude (V)	12.15[2]
Apparent dimensions (V)	10'[3]
Constellation	Sagittarius
Physical characteristics
Radius	38 ly
Designations	RCW 142, LBN 4
See also: Lists of nebulae

Sh 2-21 is an emission nebula in the constellation Sagittarius. It is part of the Sharpless Catalog assembled by Stewart Sharpless. It is associated with four infrared clusters, [DB2000] 7, [DB2000] 10, [DB2000] 11 and [DB2000] 12. Open cluster Collinder 351 is included as part of the nebula complex.^[4]

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