We determine the frequency of the ultranarrow $^{ 87}\text{ Sr}$ ${ ^{ 1}\text{ S}_{ 0}} - { ^{ 3}\text{ P}_{ 2}}$ transition by spectroscopy of an ultracold gas. This transition is referenced to four molecular iodine lines that are observed by Doppler-free saturation spectroscopy of hot iodine vapor. The frequency differences between the Sr and the I$_2$ transitions are measured with an uncertainty of 250 kHz. The absolute frequency of the $^{ 87}\text{ Sr}$ ${ ^{ 1}\text{ S}_{ 0}} - { ^{ 3}\text{ P}_{ 2}}$ ($\text{ F}'=7/2$) transition is 446648775(30) MHz and limited in accuracy by the iodine reference. This work prepares the use of the Sr ${ ^{ 1}\text{ S}_{ 0}} - { ^{ 3}\text{ P}_{ 2}}$ transition for quantum simulation and computation.
Categories: physics.atom-ph cond-mat.quant-gas