Spectrum of Sgr *A. Filled circles denote a quasi-simultaneous spectrum obtained around April 1, 2007 during a multiwavelength campaign (Yusef-Zadeh et al. 2009). The error bars on the data points indicate the variability of Sgr A*. The solid black line indicates a power law fitted to the radio data up to 43 GHz. Above 43 GHz, a flux density excess over this line is apparent. Open symbols connected by dashed lines indicate the new and quasi-simultaneous flux density measurements of May 18 and 21, 2007, from which high frequency spectral indices were derived, respectively. Note a spectral turnover between 100−230 GHz.