It passed about 28 lunar distances (LD) from the Earth on 25 December 2015. It came within about 7 LD (0.0189 AU) on 22 December 2018. Its peak brightness was about 13.13 magnitude on 16 December 2018.
Observations are planned for favorable flybys in 2021, 2024, and 2027. It passed with 14 LD (0.0363 AU) on 17 December 2021, and 34 LD (0.0884 AU) on 2 December 2024, and 54 LD (0.1382 AU) on 12 November 2027.[1]
Patrick Taylor of Arecibo Observatory suggested it could be a target for a future robotic mission.[6]
It was observed in December 2015 at a distance of 28.3 lunar distances (0.07296 AU) on December 24, and its brightest was 15.22 magnitude on December 16. It showed an elongated shape, up to 2 km wide, described as being shaped like a sweet potato.
The daily motion of (163899) 2003 SD220 in December 2018
2021
2003 SD220 passed at a distance of 14.1 lunar distances (0.03628 AU) on December 17, 2021. It was observed by the Goldstone Solar System Radar from November to December 2021.
22 November 2021
Notes
^Lightcurve plot of (163899) 2003 SD220, by Brian Warner, Palmer Divide Station, California (2015). Rotation period of 285±5 hours with a brightness amplitude of 2.2±0.1 mag. Quality Code 2+. Summary figures at the LCDB