Brief introduction of horsetail constellation

Sagittarius is a very large constellation, consisting of carina, vela and tailstock. Later, it was divided into three by Lacaille. So there are no α, β, γ, δ and ε stars. Although the stars in this constellation are not bright, there are five bright open clusters, namely M46, M47, M93, NGC2447 and NGC225 1. This constellation also has an eclipse binary star V, which varies between 4.4 and 4.9.

Among the four open clusters in this constellation, M46 is the farthest from the Earth, which is 5,700 light years, which is about the size of a full moon. Next is NGC2274, which is 4200 light years away, but the stars are denser than any cluster in the constellation, so it needs a small telescope to distinguish them. There is an open cluster, M47, less than 3 degrees east of M46, but this cluster is only 1600 light years away from the Earth, and it is very dark, and M93 is even darker than it. The brightest star cluster in the constellation is NGC245 1, and its brightest star is a yellow Supergiant star of magnitude 3.6-Sagittarius C (Sagittarius III).