Copyright © 1981 by the University of Washington Press

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The Plates

For the main part of the atlas, the photographic plates used were taken at the prime focus of the 4-meter telescope of the Kitt Peak National Observatory. They represent the ``M31 consortium'' plates taken in October 1974. All were exposed for 25 minutes on IIaO emulsion behind a Schott GG 385 filter, giving a color response similar to B of the UBV system.

Table 2 lists the plates used for the main atlas, as well as the plates used for the index charts, which were taken with the Palomar Mountain 1.2-meter Schmidt. The limiting magnitude is approximately B = 22.5 on the 4-meter plates, but because of loss in reproduction, this reduces to approximately B = 22.0 for the published charts.

The original plate scale for the 4-meter plates was 18.6 arc sec per mm and the resolution was seeing-limited to approximately 1-3 arc seconds. The Schmidt plates have a scale of 67 arc sec per mm and a resolution of approximately 3 arc seconds.

TABLE 2. The Plates
Table 2

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