UGY selected objects (blue points) along with objects selected with the UGR criterion that are excluded by the UGY criterion (red triangles). Upwards-pointing and right-pointing arrows mark upper limits in the U and G band, respectively. Objects with spectroscopic redshift in the range 2.7 <  z <  3.3 are marked as green crosses. Open triangles and open squares indicate sources at z <  2.7 and z >  3.3, respectively. Objects in the expected redshift range that are excluded by our selection are indicated in yellow.