Sky distribution of all 253 ISPY targets. PPD targets are shown in red, DEB targets in blue. Targets observed in P 96 through P 100 are marked as large filled circles. Targets observed later and with the analysis not yet included in this paper are marked as small empty circles. The grey-shaded area and dotted contours outline the Milky Way disc and bulge as traced by the COBE-DIRBE band 2 (K) zodi-subtracted all-sky map (Hauser et al. 1989). Dotted and dashed horizontal lines mark the approximate declinations for field rotations of 60° and 50°, respectively,achievable with a total observing time of 3 h scheduled around meridian passage of the star.