- L286 minutes (143 frames)
- R18 minutes (9 frames)
- B18 minutes (9 frames)
- G18 minutes (9 frames)
Messier 103 (also known as M103 or NGC 581) is a small open cluster in the constellation Cassiopeia, consisting of many faint stars. It was discovered on March 27, 1781 by Pierre Méchain and later added to Charles Messier's catalogue as his last deep-sky object.
The cluster is located 9,400 light-years from Earth and has a diameter of about 15 light-years. It contains two bright stars at its centre: the brighter one has a magnitude of 10.5, and a red giant with a magnitude of 10.8. The outer object Struve 131 is a binary star, but is not a member of the cluster. Based on the probability of gravitational binding, the cluster contains about 172 stars and is estimated to be between 12.6 and 25 million years old.
History of observations
After the discovery of M101 and M103 by Pierre Méchain, Messier later added this open cluster to his catalogue. In 1783, William Herschel described the region as containing 14-16 pl (fairly large stars) with many eS (extremely faint stars). Ake Wallenquist was the first to identify 40 stars, and Antonin Bechvar increased this number to 60. According to Arshin and Hines, the cluster contains 172 stars.
Telescopic Viewing
Messier 103 is an easy object to find, visible even through binoculars or a small telescope. The cluster appears as a nebulose spot resembling a fan shape, and its diameter is approximately 6 arcminutes (0.1°), which is about five times smaller than the diameter of the Moon. To find M103, it is recommended to aim for Rukhba or the lowest star in the characteristic "W" shape of Cassiopeia. The cluster will be located on the outside of the "W", in the field, about a third of the way to Epsilon Cassiopeiae, the end star of this asterism.
| Photo | Date | Frames | Exposure | L | R | G | B |
|---|---|---|---|---|---|---|---|
 | 07 Aug 2023 | 170 | 05:40 | 04:46 | 00:18 | 00:18 | 00:18 |
Visibility chart of Open star cluster M 103 during the day
| Date | Moon Phase | Exposure | CCD Temperature | Gain | Offset | Filter |
|---|---|---|---|---|---|---|
- 2023ixf•
- 40 Eri•
- Abell 74•
- Artemis A868 SA•
- a Canis Minoris•
- C 2020 R4 ATLAS•
- C 2020 T2 Palomar•
- C 2021 S3 (PANSTARRS)•
- Haumea (2003 EL61)•
- HCG 68•
- HCG 92•
- IC 1318B•
- IC 1396•
- IC 1795•
- IC 1805•
- IC 1848•
- IC 1871•
- IC 3322A•
- IC 342•
- IC 4015•
- IC 405•
- IC 417•
- IC 434•
- IC 443•
- IC 4703•
- IC 5070•
- IC 5146•
- IC 63•
- M 1•
- M 101•
- M 103•
- M 109•
- M 13•
- M 15•
- M 27•
- M 3•
- M 33•
- M 42•
- M 45•
- M 5•
- M 51•
- M 57•
- M 63•
- M 64•
- M 74•
- M 76•
- M 81•
- M 82•
- M 86•
- M 87•
- M 94•
- M 97•
- NGC 147•
- NGC 1491•
- NGC 1499•
- NGC 1579•
- NGC 1961•
- NGC 2146•
- NGC 2239•
- NGC 2403•
- NGC 281•
- NGC 4236•
- NGC 4565•
- NGC 4631•
- NGC 507•
- NGC 508•
- NGC 5866•
- NGC 5907•
- NGC 6503•
- NGC 6823•
- NGC 6888•
- NGC 6946•
- NGC 6992•
- NGC 6995•
- NGC 7000•
- NGC 7023•
- NGC 7129•
- NGC 7217•
- NGC 7331•
- NGC 7380•
- NGC 7538•
- NGC 7635•
- NGC 7640•
- NGC 7822•
- NGC 891•
- NGC 896•
- NGC 925•
- PGC 54559•
- Sh2-155•
- Sh2-168•
- Sh2 103•
- Sh2 109•
- Sh2 132•
- T CrB•
- UGC 6930•
- V1405 Cas•
- Vesta A807 FA•