Precision measurement of two iodine lines at 585 nm and 549 nm

The transition frequencies of thei-component of the R(99)15-1 and thew-component of the R(85)26-0 transition in the B-X system of molecular¹²⁷I₂ have been determined with an overall relative standard uncertainty of 1.3 · 10^?10. For this purpose a commercial linear dye laser has been modified and stabilized to the corresponding iodine line. This dye laser serves as a transportable frequency standard which is compared with the wavelength standards of the PTB. The evaluation of an experiment for testing special relativity at the test storage ring (TSR) in Heidelberg is based on the precision of the reported interferometric wavelength comparison.