<page_title> Metre </page_title> <section_title> Timeline </section_title> <table> <cell> Hyperfine atomic transition; 1650763.73 wavelengths of light from a specified transition in krypton-86 (11th CGPM) <col_header> Basis of definition </col_header> </cell> <cell> 1960 <col_header> Date </col_header> </cell> </table>
In 1960, the 11th CGPM defines the metre as 1650763.73 wavelengths from a transition in krypton-86 atom.