Messier 48 or M48, also known as NGC 2548, is an open cluster of stars in the equatorial constellation of Hydra.

[9] Her nephew John Herschel described it as, "a superb cluster which fills the whole field; stars of 9th and 10th to the 13th magnitude – and none below, but the whole ground of the sky on which it stands is singularly dotted over with infinitely minute points".

The metallicity of the cluster, based on the abundance of iron (Fe), is [Fe/H] = −0.063±0.007 dex, where −1 would be ten times lower than in the Sun.

[10] The cluster has a tidal radius of 63.3 ± 7.8 ly (19.4 ± 2.4 pc)[4] with at least 438[11] members and a mass of 2,366 M☉.

[4] The general structure of the cluster is fragmented and lumpy, which may be due to interactions with the galactic disk.