Harvard-Smithsonian Center for Astrophysics|
Harvard Observatory Plate Stacks
MC Series Notes
The instrument was refigured after about 3500 plates have been taken; the distance correction was thereby diminished, but the color coefficient was practically unchanged. In general, it is well to avoid plates taken before the re-figuring for accurate photometric work. All plates subsequent to MC 4171 were taken with the curved plate holder, which demonstrates [sic? diminishes?] the distance correction due to curvature of the field, but there is still a certain variation from plate to plate. These plates are to be preferred to previous ones, because of their smaller distance corrections, but it is inadvisable for precise photometry to work far from the center of an MC plate. [Doesn't that sound familiar?]
Excellent plates may be found, both blue and yellow, both single and in series with the Pole and the Harvard Standard Regions [these are regularly photographed regions with many variable stars]. In addition, a few red plates, both single, and in series with the Pole, may be found for certain regions. Note that there exists extensive material for the determination of photo visual sequences, especially for long period variables.