William Herschel discovered NGC 5484 = H III-791 on 14 Apr 1789 (sweep 921) and recorded "Two; [referring to NGC 5485] cB, R, vgmbM. Has another preceding [NGC 5484]; vF, R, nearly in the meridian 3 or 4' dist preceding." CH added the comment in her fair copy that "By the description it should be perhaps be nearly in the parallel." Although only a single position was given (matching NGC 5485], this galaxy is 3.7' west-northwest and matches the description.

Bigourdan's "corrected" position for NGC 5484 on 13 May 1899 refers to NGC 5485. Bigourdan and d'Arrest were both unsuccessful in finding NGC 5484 so Dreyer mistakenly noted in his 1912 correction list that "III 791 should probably be struck out. There is not any nebula close p [of NGC 5485]."

400/500mm - 17.5" (5/10/86): very faint, small, slightly elongated, weak concentration. Located 3.8' NW of much brighter NGC 5485 in a trio with NGC 5486.

Notes by Steve Gottlieb