 M102 was observed by Méchain, who communicated his notes to Messier.Méchain later concluded that this object was simply a re-observation of M101, though some sources suggest that the object Méchain observed was the galaxy NGC 5866 and identify that as M102.Messier's final catalogue was included in the "Connaissance des Temps pour l'Année 1784" ("Knowledge of Time"; published in 1781), the French official yearly publication of astronomical ephemerides.