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The red giant ${\delta}$ Muscae is known since 1919 to be a spectroscopicbinary, and the first and only orbit was determined in 1936, claiming theperiod to be 847 days. This was discrepant with the Hipparcos determinedastrometric orbit. Using the latest data available for this object - leading toa 100 yr time-span - we show here that the correct period is 423 d, and areable for the first time to combine the spectroscopic orbit with the Hipparcosorbit. Using all the available information, we find that the $\sim$ 1.2 solarmass red giant must have a $\sim$ 0.3 - 0.4 solar mass M dwarf companion, andthat the system will soon evolve towards a He WD binary system. Given itsrelatively short period, ${\delta}$ Muscae may be an ideal benchmark fortesting astrometric orbits obtained by Gaia for very bright stars.

${\delta}$ MUS Revisited:Rectifying an 82 Yr-Old Mistake