Difference between apparent electron release time (TSA) and the time derivative maximum of X-ray intensity as a function of flare longitude for the 1996–2016 events. Solar cycle 23 (1996–2008) events are marked in red, solar cycle 24 (2009–2016) events in blue. Negative abscissa values refer to eastern and positive values to western longitude. Note the outlying data point near the lower right-hand corner.