1999 || Socorro || LINEAR || — || align=right | 5.0 km || |-id=274 bgcolor=#E9E9E9 | 56274 || || — || May 15, 1999 || Socorro || LINEAR || — || align=right | 7.1 km || |-id=275 bgcolor=#d6d6d6 | 56275 || || — || May 13, 1999 || Socorro || LINEAR || — || align=right | 5.9 km || |-id=276 bgcolor=#E9E9E9 | 56276 || || — || May 14, 1999 || Socorro || LINEAR || — || align=right | 5.4 km || |-id=277 bgcolor=#E9E9E9 | 56277 || || — || May 12, 1999 || Socorro || LINEAR || — || align=right | 4.6 km || |-id=278 bgcolor=#d6d6d6 | 56278 || 1999 KB || — || May 16, 1999 || Woomera || F. B. Zoltowski || — || align=right | 5.9 km || |-id=279 bgcolor=#E9E9E9 | 56279 || || — || May 17, 1999 || Catalina || CSS || PAE || align=right | 5.3 km || |-id=280 bgcolor=#E9E9E9 | 56280 Asemo || || || May 22, 1999 || Oaxaca || J. M. Roe || — || align=right | 4.1 km || |-id=281 bgcolor=#E9E9E9 | 56281 || || — || May 18, 1999 || Socorro || LINEAR || — || align=right | 5.1 km || |-id=282 bgcolor=#E9E9E9 | 56282 || || — || May 18, 1999 || Socorro || LINEAR || EUN || align=right | 4.0 km || |-id=283 bgcolor=#fefefe | 56283 || || — || June 4, 1999 || Socorro || LINEAR || PHO || align=right | 3.8 km || |-id=284 bgcolor=#E9E9E9 | 56284 || || — || June 5, 1999 || Nachi-Katsuura || Y. Shimizu, T. Urata || — || align=right | 8.1 km || |-id=285 bgcolor=#d6d6d6 | 56285 || || — || June 6, 1999 || Kitt Peak || Spacewatch || KAR || align=right | 3.3 km || |-id=286 bgcolor=#d6d6d6 | 56286 || || — || June 8, 1999 || Socorro || LINEAR || EUP || align=right | 11 km || |-id=287 bgcolor=#d6d6d6 | 56287 || || — || June 8, 1999 || Socorro || LINEAR || — || align=right | 3.7 km || |-id=288 bgcolor=#E9E9E9 | 56288 || || — || June 9, 1999 || Socorro || LINEAR || — || align=right | 6.2 km || |-id=289 bgcolor=#fefefe | 56289 || || — || June 9, 1999 || Socorro || LINEAR || PHO || align=right | 2.6 km || |-id=290 bgcolor=#d6d6d6 | 56290 || || — || June