Method for positioning a target portion of a substrate with respect to a focal plane of a projection system

A lithographic apparatus comprising:

• a support constructed to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam;
• a substrate table constructed to hold a substrate;
• a projection system configured to project the patterned radiation beam onto a target portion of the substrate;
• and
• a level sensor configured to perform height measurements of at least part of the substrate to generate height data, for use in positioning a target portion of the substrate with respect to a focal plane of the projection system, wherein the lithographic apparatus is adapted to use predetermined correction heights to compute corrected height data for the height data.