Exposure time map of the MXDF. The blue circles are the MXDF-selected objects, the pink triangles indicate the UDF-10-selected targets and the green squares the MOSAIC-selected objects (see Sect. 2.2). The field is coloured by exposure time in hours, from 0 h to 140 h. The red contour represents the 100 h limit of the field. The solid and dashed white contours show the 30 h and 10 h exposure time of the MXDF, respectively. The UDF-10-selected objects present in the deepest part of the field have their Lyα line in the AO gap.