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In page Charles Messier:

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The final version of the catalogue was published in 1781, in the 1784 issue of Connaissance des Temps.[4][5][6] The final list of Messier objects had grown to 103. On several occasions between 1921 and 1966, astronomers and historians discovered evidence of another seven objects that were observed either by Messier or by Méchain, shortly after the final version was published. These seven objects, M 104 through M 110, are accepted by astronomers as "official" Messier objects.[citation needed]