Messier 45 - The Pleiades Cluster
Acquisition Details (Top)
Date: 2024/02/23
Exposure: 139 × 60” (~2.32 hours)
Bortle Scale: 2
Gear: Sony A7iii, Sony 200-600mm @600mm, Sky Watcher Star Adventurer Pro 2i
Acquisition Details (Bottom)
Date: 2026/01/15
Exposure: 123 × 120” + 45 × 60”(~4.85 hours)
Bortle Scale: 6
Gear: ZWO ASI2600MC Duo, Askar 130PHQ, Sky Watcher EQ6-R Pro, ZWO ASIAIR Plus, ZWO EAF
Discovered: Known pre-historically. Mentioned by Greek poet Homer around 750 B.C. and Greek poet Hesiod around 700 B.C., Observed and cataloged on March 4, 1769 by French Astronomer Charles Messier. [1] [2]
Object Type: Open Cluster [3]
Apparent Magnitude: 1.6 [3]
Distance: 445 light-years away [3]
Other Designations: The Seven Sisters, Mel 22, Cr 42 [4]
Constellation: Taurus [3]
Notes from Messier:
March 4, 1769. 45. 3h 33m 48s (53d 27' 04") +23d 22' 41"
A cluster of stars, known by the name of the Pleiades. The position reported is that of the star Alcyone. [2]
[Mem. Acad. for 1771, p. 451-452 (first Messier catalog)]
One can say the same [as for M44] for the Pleiades, by reporting their position by that of the star Eta, with its right ascension becoming, for March 4, 1769, 53d 27' 4", & its declination 23d 22' 41" north.
[p. 458] 1769.Mar. 4. RA: 53.27. 4, Dec: 23.22.41.B. Cluster of stars known by the name Pleiades: the position reported is that of the star Alcyone. [2]
References:
[1] Students for the Exploration and Development of Space (2025, February 23). Messier 45. Charles Messier's Catalog of Nebulae and Star Clusters. Retrieved May 31, 2026, from http://www.messier.seds.org/m/m045.html
[2] Students for the Exploration and Development of Space (2025, February 2). Messier 45, Observations and Descriptions. Charles Messier's Catalog of Nebulae and Star Clusters. Retrieved May 31, 2026, from http://www.messier.seds.org/Mdes/dm045.html
[3] NASA (2025, December 8). Messier 44. Messier 44. Retrieved May 31, 2026, from https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-45/
[4] Stellarium (n.d.). Messier 45. Stellarium Web. Retrieved May 31, 2026, from https://stellarium-web.org/