R.J. Mitchell and George Johnstone Stoney, LdR's assistants, discovered NGC 5143 on 17 Apr 1855. They noted "a third vF neb [with NGC 5142 and 5143], nearly north of the following one NGC 5142]." A sketch clearly matches this trio of galaxies, although offsets were not measured.

400/500mm - 17.5" not seen in thin clouds.

Notes by Steve Gottlieb