Simplify the following text for a Grade 7 native English-speaking person.
Original: In 1882 , Vogel became the Director at the Astrophysical Observatory Potsdam and he is best known for some work there in 1890 .
Simplified: In 1882 , Vogel became the Director at the Astrophysical Observatory Potsdam . and he is best known for a discovery he made there in 1890 .