Open Cluster Messier 103

Messier 103
Messier 103: Section of the STScI Digitized Sky Survey. Here could be your picture. [147]


The open star cluster M 103 was discovered by Pierre Méchain on 27 March 1781. He described it as a «cluster of stars between ε and δ of the legs of Cassiopeia». [281]

Physical Properties

M 103 is of the Trumpler type III2p. It is about 7'100 light years away from us and is approaching us at a speed of 45 km/s. A striking feature is the double star Struve 131 (ADS 1209, HD 9311) in the northwest of the cluster. Its two stars are 7.2 mag and 9.8 mag bright and 13.9 arc seconds apart. The double star does not belong to the cluster. [145]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation NGC 581
Type OCL (III2p)
Right Ascension (J2000.0) 01h 33m 23.0s
Declination (J2000.0) +60° 39' 30"
Diameter 6 arcmin
Visual magnitude 7.4 mag
Metric Distance 2.194 kpc
Dreyer Description Cl, pL, B, R, Ri, st 10…11
Identification, Remarks h 126; GC 341; M 103; OCL 326

Finder Chart

The open star cluster M 103 is located in the constellation Cassiopeia between the stars Segin (ε Cassiopeiae) and Ruchbah (δ Cassiopeiae). The constellation is highest in the months of July to January.

Finder Chart Open Cluster Messier 103
Open Cluster Messier 103 in constellation Cassiopeia. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Objects Within a Radius of 15°