Fluxes of Q0957+561A (top panel) and Q0957+561B (bottom panel) in the g and r bands of the SDSS photometric system. Circles denote the g-SDSS light curves and squares represent the r-SDSS records. The whole optical data set is separated into two parts by a vertical dashed line: LQLM I (2005–2007) and LQLM II (2008–2010). The new effort in the 2008–2010 period doubles our contribution to the two-colour variability database of Q0957+561. We also highlight the LRT main fluctuations using grey rectangles (see main text).