|| align=right | 5.6 km || |-id=255 bgcolor=#fefefe | 40255 || || — || February 12, 1999 || Prescott || P. G. Comba || — || align=right | 2.0 km || |-id=256 bgcolor=#fefefe | 40256 || || — || February 10, 1999 || Socorro || LINEAR || H || align=right | 1.4 km || |-id=257 bgcolor=#fefefe | 40257 || || — || February 10, 1999 || Socorro || LINEAR || — || align=right | 1.9 km || |-id=258 bgcolor=#fefefe | 40258 || || — || February 12, 1999 || Socorro || LINEAR || — || align=right | 1.8 km || |-id=259 bgcolor=#fefefe | 40259 || || — || February 10, 1999 || Socorro || LINEAR || V || align=right | 3.0 km || |-id=260 bgcolor=#E9E9E9 | 40260 || || — || February 10, 1999 || Socorro || LINEAR || — || align=right | 3.6 km || |-id=261 bgcolor=#fefefe | 40261 || || — || February 12, 1999 || Socorro || LINEAR || V || align=right | 2.7 km || |-id=262 bgcolor=#C2FFFF | 40262 || || — || February 7, 1999 || Kitt Peak || Spacewatch || L4 || align=right | 14 km || |-id=263 bgcolor=#FFC2E0 | 40263 || || — || March 18, 1999 || Kitt Peak || Spacewatch || AMO +1km || align=right data-sort-value="0.95" | 950 m || |-id=264 bgcolor=#fefefe | 40264 || || — || March 20, 1999 || Socorro || LINEAR || H || align=right | 1.1 km || |-id=265 bgcolor=#fefefe | 40265 || || — || March 19, 1999 || Socorro || LINEAR || — || align=right | 2.9 km || |-id=266 bgcolor=#fefefe | 40266 || 1999 GS || — || April 5, 1999 || Višnjan Observatory || K. Korlević || NYS || align=right | 4.2 km || |-id=267 bgcolor=#FFC2E0 | 40267 || || — || April 10, 1999 || Socorro || LINEAR || APO +1km || align=right | 1.6 km || |-id=268 bgcolor=#fefefe | 40268 || || — || April 10, 1999 || Anderson Mesa || LONEOS || FLO || align=right | 1.8 km || |-id=269 bgcolor=#fefefe | 40269 || || — || April 6, 1999 || Socorro || LINEAR || FLO || align=right | 1.7 km || |-id=270 bgcolor=#fefefe | 40270 || 1999 JE || — || May 6, 1999 || Socorro || LINEAR || H || align=right | 1.7 km || |-id=271 bgcolor=#FA8072 | 40271 || 1999 JT || — || May 4,