align=right | 3.8 km || |-id=496 bgcolor=#d6d6d6 | 20496 Jeník || || || August 22, 1999 || Ondřejov || L. Kotková || — || align=right | 5.3 km || |-id=497 bgcolor=#d6d6d6 | 20497 Mařenka || 1999 RS || || September 4, 1999 || Ondřejov || L. Kotková || VER || align=right | 8.7 km || |-id=498 bgcolor=#E9E9E9 | 20498 || || — || September 5, 1999 || Višnjan Observatory || K. Korlević || — || align=right | 5.2 km || |-id=499 bgcolor=#d6d6d6 | 20499 || || — || September 6, 1999 || Višnjan Observatory || K. Korlević || KOR || align=right | 4.2 km || |-id=500 bgcolor=#fefefe | 20500 Avner || || || September 4, 1999 || Catalina || CSS || FLO || align=right | 3.0 km || |} 20501–20600 |-bgcolor=#E9E9E9 | 20501 || || — || September 7, 1999 || Socorro || LINEAR || — || align=right | 3.2 km || |-id=502 bgcolor=#E9E9E9 | 20502 || || — || September 7, 1999 || Socorro || LINEAR || — || align=right | 14 km || |-id=503 bgcolor=#d6d6d6 | 20503 Adamtazi || || || September 7, 1999 || Socorro || LINEAR || — || align=right | 9.2 km || |-id=504 bgcolor=#E9E9E9 | 20504 || || — || September 7, 1999 || Socorro || LINEAR || EUN || align=right | 4.2 km || |-id=505 bgcolor=#d6d6d6 | 20505 || || — || September 7, 1999 || Socorro || LINEAR || — || align=right | 11 km || |-id=506 bgcolor=#E9E9E9 | 20506 || || — || September 7, 1999 || Socorro || LINEAR || MIT || align=right | 6.7 km || |-id=507 bgcolor=#fefefe | 20507 || || — || September 7, 1999 || Socorro || LINEAR || — || align=right | 3.0 km || |-id=508 bgcolor=#fefefe | 20508 || || — || September 7, 1999 || Socorro || LINEAR || — || align=right | 5.7 km || |-id=509 bgcolor=#d6d6d6 | 20509 || || — || September 7, 1999 || Socorro || LINEAR || HYG || align=right | 9.9 km || |-id=510 bgcolor=#d6d6d6 | 20510 || || — || September 7, 1999 || Socorro || LINEAR || EMA || align=right | 11 km || |-id=511 bgcolor=#fefefe | 20511 || || — || September 8, 1999 || Višnjan Observatory || K. Korlević || — || align=right | 3.5 km || |-id=512 bgcolor=#d6d6d6 | 20512 Rothenberg || || || September 10, 1999 || Drebach || A. Knöfel