DIGITIZATION AND DISTRIBUTION OF THE LARGE PHOTOGRAPHIC SURVEYS

All-sky photographic surveys made with the large Schmidt telescopes have long been a major resource for research support; within a few years the second-generation surveys now in progress with the UK and the Oschin (Palomar) Schmidts will generalize this coverage to at least two epochs and two passbands. The quantitative use of these plate collections depends on their digitization. For the five modern high-speed systems currently devoted to this work (APM, Cambridge; SuperCosmos, ROE; GAMMA, STScI; APS, Minnesota; and PPM, Flagstaff), the machine properties, together with the associated accomplishments and plans are summarized. Additional discussion topics include the complementary role of object lists (i.e., catalogs) and pixel data (rasters), naming conventions, the need for an adequate level of independent checking, together with the construction of a master object list, and the future of measuring photographic plates.