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Discovered 1771 by Charles Messier.

Open cluster Messier 48 (M48, NGC 2548) is a conspicuous open cluster in thehead of the extended constellation Hydra, almost on its border to Monoceros.

This open cluster was discovered byCharles Messier andcataloged by him on February 19, 1771.However, as he did an error in data reduction, he gave a wrong position inhis catalog so that the object wasmissing untilOswald Thomas identified it in 1934, and independentlyT.F. Morris in 1959. The identification of M48 by Oswald Thomas was confused by some historians, who have claimed erroneously instead that he had identified M47.As M48 was lost, two independent rediscoveries occurred:First,Johann Elert Bode apparentlyfound it in or before 1782, and second,Caroline Herschel independentlyrediscovered it on March 8, 1783,and added it to her small list as No. 5.This latter discovery was published by Caroline's famous brother,William Herschel, who included it inhis catalog as H VI.22 on February 1, 1786.

M48 is a quite conspicuous object and should be a naked-eye object undergood conditions. The smallest binocular, or telescopes, show a large group ofabout 50 stars brighter than mag 13, the total number being at least 80. Themore concentrated core extends over about 30 arc minutes, while the outskirtsreach out to about 54', corresponding to a linear diameter of 23 light yearsat its distance of 1,500 light years (given so by Mallas/Kreimer and KennethGlyn Jones, while the Sky Catalog 2000 has 2,000 light years).M48 was classified as of Trumpler type I,2,m (Sky Catalog 2000),I,2,r (Glyn Jones) or I,3,r (Götz).

The age of M48 was estimated to amount about 300 million years; the hottest star is of spectral type A2 and mag 8.8; its luminosity is about 70 times that of the Sun. M48 moreover contains 3 yellowgiants of spectral types G-K.

NGC Online data for M48

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Hartmut Frommert
Christine Kronberg
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Last Modification: March 11, 2009

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