Redshift z=5.5 Quasar

The most distant quasar known at the time, and the subject of an article in the NOAO March 2000 newsletter, RD300 was identified as a candidate using these images from a survey carried out with the Kitt Peak National Observatory's Mayall 4-meter telescope. The quasar is visible only in the right-hand, I-band (far red) image, and not in the left, R-band (red) image. This happens when the object's redshift is large enough to move significant energy emission out of the red band while keeping some in the far red, which happens at about z=5.