What exactly is the purpose of Arthapatti pramana?

Jill: Hale-Bopp Comet, now in a part of its orbit relatively far from the Sun, recently flared brightly enough to be seen by telescopes. No comet has ever been observed to flare so far from the Sun before, so such a flare must be highly unusual. Sara: Hogwash. Usually, no one bothers to try to observe comets when they are so far from the Sun. This flare was observed only because an observatory was tracking Hale-Bopp Comet very closely.

Sara challenges Jill's reasoning by