Isn’t that galaxy also rotating? So if you wanted to hit the far right corner of that galaxy, then don’t you have to calculate where it actually is now, since it took so many light years from that part of the galaxy to reach us.
Then, you’d have to calculate where that part of the galaxy will be, by the time you reach it. Then, you aim yourself at those coordinates, and hope you don’t have any mechanical issues that will prevent you from gravitationally locking on to your destination star system.
