A lithographic projection apparatus includes a beam production system for projecting a patterned beam of radiation onto a target portion of a substrate, and a support table for supporting an article. The support table has a support surface and an array of protrusions extending from the support surface to support the article on the protrusions. The apparatus also includes a detector for detecting height deviations of the protrusions that affect a surface flatness of the article, a height adjustment device arranged to independently modify a height of the individual protrusions when the support table is operable in the apparatus, and a controller coupled between the detector and the height adjustment device and arranged to control the height adjustment device to adjust the height of the protrusions corresponding to the detected height deviations of the protrusions that affect the surface flatness of the article.