Accurate Photometry with Digitized Photographic Plates of the Moscow Collection

Abstract

AbstractPhotographic plate archives contain a wealth of information about the positions and brightness of celestial objects decades ago. Plate digitization is necessary to make this information accessible, but extracting it is a technical challenge. We have developed algorithms to extract photometry with an accuracy of better than ∼0.1 mag. in the range 13 < B < 17 mag from photographic images obtained in 1948–1996 with the 40-cm Sternberg Institute astrograph (30 × 30 cm plate size, 10 × 10 deg field of view) and digitized using a flatbed scanner. The extracted photographic light-curves are used to identify thousands of new high-amplitude variable stars (>0.2 mag). The algorithms are implemented in the free software VaST available at http://scan.sai.msu.ru/vast/