Classification of GRB 150309A The conventional scheme of GRB classification based on the spectral hardness-duration distribution (top left), minimum variability timescale-duration distribution (top right), spectral lag-luminosity correlation (bottom left), and episode-wise Amati correlation (bottom right). The dashed lines show the boundary between long and short families of GRBs. The high-energy properties of GRB 150309A (displayed with red and blue squares) are common among long soft bursts.