Simplify the following text for a Grade 3 native English-speaking person.
Original: It was discovered by Matthew J. Holman , Brett J. Gladman , et al . on August 14 , 2002 , though it went unnoticed until 2003 .
Simplified: It was found by Matthew J. Holman , Brett J. Gladman , et al . on August 14 , 2002 , though it went unnoticed until 2003 .