sighter

noun4

1. •
   One who has sighted or seen something.

   • He would have been a great help in the task of examning the reports submitted and interviewing the sighters. — 1965
2. •
   A trial shot in rifle, artillery shooting, or sports like football, to set the range, targeting etc.

   • Kane looked in the mood, testing the goalkeeper, Hannes Thor Halldórsson, with an early sighter and then being denied what appeared to be a good goal on six minutes by an offside flag. — 2020
3. •
   A sight on a weapon.
4. •
   A targeteer.