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Figure 1: NIR flux variation of Sgr A* during the coordinated Chandra/VLT observations of the Galactic Center. Upper panel: dereddened NIR flux vs. time of Sgr A* (black), S1 (blue), S2 (red) and of the average of random measurements in a region about 0.5''west of Sgr A* with no detectable source (green). Error bars were estimated from aperture photometry with two apertures. The observations started on 19 June 2003 at 23:51:15 (UT). Middle panel: as upper panel, but smoothed with a sliding window, averaging 4 measurements at a time. Lower panel: as middle panel, but corrected for remnant correlated flux variations.

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In the text

Figure 2: Each panel shows the average of eight Lucy-Richardson deconvolved and beam restored images taken at different intervals of the measurements (see light curves in Fig. 1). The UT start times of the first images in each series are indicated in the panels. Top: beginning of the observations. Middle: about 25 min after begin of the observations. Bottom: around 80 min after begin of the observations. One can also see how the image quality improved when comparing the upper and middle/lower panel images. Sgr A* can be seen as a flaring source in the top and middle panels. The field of view is 1.43'' (72 light days) times 0.85'' (43 light days).

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In the text

	Figure 3: X-ray light curve as observed by Chandra in the 1.0 aperture. The bin interval is 10 min. The solid straight line represents the X-ray IQ-state count rate. The background (lower points) was steady throughout the observations which started on 19 June 2003 at 18:46:38 (UT).
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In the text

Figure 4: The X-ray and NIR light curves plotted with a common time axis. See text and captions of previous figures. Straight solid lines in the inserted box represent the 0.00, 0.01, and 0.02 counts per s levels. The straight dashed line represent the X-ray IQ-state flux density level. The NIR observations started on 19 June 2003 at 23:51:15 (UT); see caption of Fig. 1. The NIR data started 0.38 min before the midpoint of the highest X-ray data point.

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In the text

	Figure 5: Bayesian blocks representation (solid line) of the X-ray light curve (dashed line) using 157.052 s bins. Two change points detected with 99.927% confidence indicate a flare event around midnight during the interval 279 to 321 min into the observation. The time series starts on 19 June 2003 at 18:46:38 (UT).
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In the text

Figure 6: Cross-correlation between the NIR data (40 s bins; 20 s integration time per image) and the X-ray data (10 min bins). At a >5 level both light curves indicate a simultaneous flare event around midnight corresponding to a time delay of less than 15 min (see text). In Fig. 6 we cross-correlated only the flare data that overlap in time. The offsets are given in minutes with respect to the beginning of the NIR data at 19 June 23:51:15 UT. The plot is limited by this start time to the left.

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In the text