Time Lag in Intra-Day Variability of Sgr A* between the Light Curves at
  90 and 102GHz
  We performed the observation of the flux densities of SgrA* at 90 and 102GHz
in order to detect the time lag between these frequencies using the Nobeyama
Millimeter Array, which was previously reported at lower frequencies. We
detected a radio flare during the observation period on 6 April 2005 and
calculated the z-transformed discrete correlation function between the light
curves. The time lag between these frequencies was not detected. If the
expanding plasma model which explains the time lag at lower frequencies is
valid, the light curve at 90GHz would be delayed with respect to the one at
102GHz. This result suggests that the plasma blobs ejected near the Galactic
Center black hole may be widely diverse especially in optical thickness.
Another possibility is that the major portion of the flux above 100GHz does not
originate from the blobs.
