Talk to Cayde-6
Speak to Cayde-6 in the Hall of Guardians at the Tower.
"Wait patient. Hold real still. As long as you have to. Longer, if you can. You only have seconds to get it done. Wait 'til they're right where you want them.
Let them get comfortable, let them think they own the place. Then, take the shot. It's the only way to be sure."