Confidence contours for Sgr A* spectral parameters. Contours are the confidence levels of 68% (dotted line), 90% (solid line), and 99% (dashed line) for the two parameters in the graph. The three sets of confidence contours represent the 2011 March 30 flare (black lines and asterisk), the 2007 April 4 flare (light gray lines and X point), and the 2002 October 3 flare (dark gray lines and cross point).