"Capture Opha Superior" is a mission objective in the story mission "Sterwin Forever" in Borderlands: The Pre-Sequel
Head to the Northern edge of the search area on the upper level of Eleseer. Head over to the one pillar in that area. You will find the Opha Superior waiting or raising from a hatch in the ground.
Opha Superior is the final monster you need to capture. These are difficult because of their higher health, shield and spawns. These can release Sera Guardians and a variety of Puttis.
Once again, get the Opha Superior around 25% health then throw the mission grenade at it to capture it. It will become: Trapped Opha Superior:
Sterwin Forever Mission Objectives
Turn in: Sterwin