The 12923 Zephry was discovered on April 11, 1999 at Anderson Mesa Stn., an astronomical observatory established in 1959 as a dark-sky observing site for Lowell Observatory.
It was discovered on 11 April 1999, by astronomers of the Lowell Observatory Near-Earth Object Search at Anderson Mesa Station near Flagstaff, Arizona. Anderson Mesa Station is an astronomical observatory established in 1959 as a dark-sky observing site for Lowell Observatory. 
