Simplify the following text for a Grade 11 native English-speaking person.
Original: Examination of past photographic records showed that the star displayed a measurable increase in magnitude on about 8 % of the images , making it the most active flare star then known .
Simplified: Past photographic records showed that the star displayed a measurable increase in magnitude about 8 % of the time , making it the most active flare star then found .