  Emission from Sgr A* is highly variable at both X-ray and infrared (IR)
wavelengths. Observations over the last ~20 years have revealed X-ray flares
that rise above a quiescent thermal background about once per day, while faint
X-ray flares from Sgr A* are undetectable below the constant thermal emission.
In contrast, the IR emission of Sgr A* is observed to be continuously variable.
Recently, simultaneous observations have indicated a rise in IR flux density
around the same time as every distinct X-ray flare, while the opposite is not
always true (peaks in the IR emission may not be coincident with an X-ray
flare). Characterizing the behaviour of these simultaneous X-ray/IR events and
measuring any time lag between them can constrain models of Sgr A*'s accretion
flow and the flare emission mechanism. Using 100+ hours of data from a
coordinated campaign between the Spitzer Space Telescope and the Chandra X-ray
Observatory, we present results of the longest simultaneous IR and X-ray
observations of Sgr A* taken to date. The cross-correlation between the IR and
X-ray light curves in this unprecedented dataset, which includes four modest
X-ray/IR flares, indicates that flaring in the X-ray may lead the IR by
approximately 10-20 minutes with 68% confidence. However, the 99.7% confidence
interval on the time-lag also includes zero, i.e., the flaring remains
statistically consistent with simultaneity. Long duration and simultaneous
multiwavelength observations of additional bright flares will improve our
ability to constrain the flare timing characteristics and emission mechanisms,
and must be a priority for Galactic Center observing campaigns.
