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Messier 103 is a rather small and far away open cluster. It is located in the constellation Cassiopeia, close to the bright delta Cas (mag +2.81, eclipsing binary). This cluster has 172 confirmed stars, out of which, a prominent red giant star, of spectral type M6 III (located near its center) as well as several type B blue super giants. The bright blue star located in the upper right corner of the cluster (ADS 1209) is a foreground star and does not belong to it. Its distance has been estimated at 10,000 ly and it is a pretty young cluster, about 25 million years old.
Additional Information
Object
Name(s): Messier 103. M103. NGC 581
Type: Open Cluster
RA: 01h 33m 22s
Dec: +60º 38’ 53”
Constellation: Cassiopeia
Size (arcmin): 6.5 arcmin
Magnitude: +7.4
Distance: 10,000 ly
Image
Date: 2020-10-25 to 2020-11-11
Location: Curiosity2 Observatory, New Mexico Skies, Mayhill, NM, USA
Size (arcmin): 32×32 arcmin
Telescope: 24” (61 cm) f/6.5 Reflector
Camera: FLI PL16803 (4096x4096pix)
Guiding: Astrodon MonsterMOAG off-axis guider
Total exposure: 9h 20m (L: 3h 10m; RGB: 6h 10m)
Processing: CCDStack, Photoshop CC 2021