Pokemon Go players have found a trick to "locking in" a target circle so they can more easily hit excellent throws.
Hitting a Pokemon with an "Excellent" throw is one of the easiest ways to increase a player's chances of catching a Pokemon in Pokemon Go. An "excellent" hit gives players a 1.9x catch bonus, which nearly doubles their chances of catching a Pokemon. However, excellent throws require both timing and skill, as the targeting window is constantly shrinking and needs to be at its smallest size in order to trigger the excellent bonus.
However, there is a trick to "locking in" an excellent throw so that players don't need to worry about timing their throw. If players hold down on a Poke Ball and then releases it without throwing when the targeting circle hits the excellent radius, it will "lock" the targeting circle at that radius provided that players wait to throw their Poke Ball until a Pokemon attacks. If a player times their throw correctly, Pokemon Go won't reset the circle, which means that players can automatically score an excellent hit... provided they have good aim.
Recently, a Redditor named "DaniTerrazas" made up a handy infographic showing how the trick works:
Locking Target Trick - The Visual Manual from TheSilphRoad
While some Pokemon Go players have known about the "target lock" trick for months, it hasn't spread as widely as other Pokemon Go tricks. Many Pokemon Go YouTubers use the trick, but don't often explain exactly why they wait until immediately after a Pokemon attacks to throw a Poke Ball.
The "target lock" trick does require a bit of timing, but players should be able to pick it up after just a few tries. Players who are hunting specific Pokemon should learn the Pokemon's attack animations so they can time their throw accordingly!