Frequency of the ultranarrow 1S0 - 3P2 transition in 87Sr

We determine the frequency of the ultranarrow 87Sr 1S0 - 3P2 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 I2 transitions are measured with an uncertainty of 0.5MHz. The absolute frequency of the 87Sr 1S0 - 3P2 (F′=7/2) transition is 446648775(30) MHz and limited in accuracy by the iodine reference. This work prepares the use of the Sr 1S0-3P2 transition for quantum simulation and computation.