The Associated Press news story published on March 13, 1930 reported that the first photographic image of a previously unknown object in space was made on January 21 at the Lowell Observatory in Flagstaff, Arizona. -- see "Ninth Planet is Found Far from Neptune" (AP). Hartford Courant. March 14, 1930. https://www.courant.com/courant-250/moments-in-history/hc-march-13-1930-pluto-discovered-20140305-htmlstory.html
This object was named Pluto in 1930. Did you know that an Italian astronomer, Emilio Bianchi, is credited with proposing the name we all know. -- see "Italian Scientists Propose 'Pluto' as New Planet's Name" (AP). Hartford Courant. March 25, 1930; and see "Emilio Bianchi," Pontifical Academy of Sciences. http://www.casinapioiv.va/content/accademia/en/academicians/deceased/bianchi.html
Pluto was called a planet between 1930 and 2006. -- see "February 18, 1930" https://www.history.com/this-day-in-history/pluto-discovered