Plot of flux density versus time for Sgr A* and nearby quasar NRAO 530 at 22, 43, and 86 GHz. Two filled arrows indicate times of NIR flares detected on May 15 (Eckart et al. 2008a) and 17. There is another possible mm flare (dashed arrow) on May 19 (Kunneriath et al. 2010). In boxes, the variability index m is given for Sgr A* and NRAO 530 at each frequency. The stationarity of the flux densities of NRAO 530 characterize the quality and repeatability of the overall amplitude calibration.