There is an exercise at De Peel, with observers from Poland and Hungary, which is probably the reason why the A319 and C295 were at NRN this day.
According to EHDP notams the exercise will run until 11 February, so it's possible that the air forces are coming next weekend again to pick up there observers. Purely based on thoughts so don't quote me on it if it's not true, the exercise may take longer than the notams suggest
Between 18:10 and 18:40 3 EC135s of the German Army landed, they will do a night flying excercise later this evening, seemingly via Düsseldorf back to Bückeburg.
Visually: 8254, 8257 and 8261