Delay-Doppler image of asteroid 2003 SD220 as observed from the Arecibo Observatory using the NASA-funded planetary radar system on December 3 – 5 and December 14 – 15, 2015.
NASA
2015-12
<a rel="nofollow" class="external free" href="https://sservi.nasa.gov/articles/silent-night-asteroid-2003-sd220-sleighs-by-earth-on-christmas-eve/">https://sservi.nasa.gov/articles/silent-night-asteroid-2003-sd220-sleighs-by-earth-on-christmas-eve/</a>