Simplify the following text for a Grade 14 native English-speaking person.
Original: Due to the greater photographic resolution allowed by a closer approach , most observations of the moons , rings , magnetic fields , and the radiation belt environment of the Jovian system were made during the 48-hour period that bracketed the closest approach .
Simplified: Due to the greater resolution allowed by close approach , most observations of the moons , rings , magnetic fields , and radiation environment of the Jupiter system were made in the 48-hour period bracketing closest approach .