Does he really have to do a lot of mental calculations, or does he just have to remember that "the satellite as it is currently positioned comes into view of my

Does he really have to do a lot of mental calculations, or does he just have to remember that "the satellite as it is currently positioned comes into view of my friend Bob's observatory in Canberra an hour and 15 before he goes home for the day, at 3:45PM local time... and with the way we are moving in relation to each other, it has been coming into view approximately 36 seconds earlier each day that passes."