[Previous] | [Session 10] | [Next]
K. M. Barkume (Reed Coll. & Maria Mitchell Obs.), V. Strelnitski (Maria Mitchell Obs.)
Maria Mitchell Observatory (MMO) has started a complete digitization of its archive of ca. 8,000 photographic plates obtained with the MMO 7.5-inch Cooke refractor from ca. 1920 to 1990. The MMO plates, having a field of view of about 10 deg, are especially numerous for Sgr, Sct, and Cyg. The catalog of the plates is to be put on our web site, www.mmo.org. The image files (in TIFF or FITS format) will be available, upon request, starting in summer 2002, when we plan to have the digitization completed. A commercially available scanner, AgfaScan T5000, is used for this project. It provides resolution of up to 2,500 ppi, corresponding to about 10 microns on the plate. In order to determine whether digitization with this scanner entails any serious losses of information, we carried out photometric measurements of several scanned plates containing the open cluster M25. We found that the simplest eye photometry of standard stars from this cluster on the digitized plate images is nearly as precise as on the plates directly. Previously, it was demonstrated (BAAS, vol.30, n4, p. 1266, abstract 11.11) that the eye photometry of photographic plates is not less precise than other methods (microphotometry; numerical reduction of digitized images). We conclude that digitization with T5000 provides a copy of the original plate completely adequate for photmetry. This project was supported by the NSF/REU grant AST-9820555 and the Nantucket Maria Mitchell Association.
The author(s) of this abstract have provided an email address for comments about the abstract: kristina.barkume@reed.edu