Published online by Cambridge University Press: 25 May 2016
Sgr A∗, the enigmatic radio source located at the dynamical center of the Galaxy, is firmly detected in the frequency range of ∼ 1 – few 102 GHz. For ∼ 0.5 – 1 GHz and in the MIR range only significant upper limits of the flux density are known. Between ∼ 1.5 and 600 GHz the time averaged flux density Sv is proportional to v 1/3 (v: frequency). For frequencies higher than ∼ 600 GHz as well as for those lower than ∼ 1.5 GHz, Sv drops sharply.