On the Discovery Claim of a New z > 7 Quasar

Abstract

Koptelova & Hwang (K22) recently claimed a new quasar discovery at z = 7.46. After careful consideration of the publicly available data underlying K22's claim, we find that the observations were contaminated by a moving solar system object, likely a main-belt asteroid. In the absence of the contaminated photometry, there is no evidence for the nearby, persistent WISE source being a high-redshift object; in fact, a detection of the source in DESI Legacy Imaging Surveys z-band rules out a redshift z > 7.3. We present our findings as a cautionary tale of the dangers of passing asteroids for photometric selections.