Systematic Corrections to Photographic Magnitudes of Polar Stars

Provisional systematic corrections for the reduction of six catalogues of photo- graphic magnitude to the international system-Greenwich i, Simeis, Harvard-Payne, Leiden-De Sitter, Gottingen A klinometrie, and Yerkes A ctinometry-have been tested with the aid of a working list of magnitudes for 373 stars (WPg) based on these correc- tions. WPg was compared with (a) Harvard Catalogue of Photographic Magnitudes of Bright Stars North of +57?5 (HPP) (Tables I, II), and (b) magnitudes from four plates of the polar region taken by F. E. Ross (RPg) (Tables III-V). Further, the RPg magnitudes of 21 NPS stars were compared directly with the international standards for these stars (Table VI). These comparisons indicate a zero-point correction of o.or mag. in WPg, and hence in the systematic corrections underlying WPg; and also a change in certain extrapolated corrections to Greenwich and Simeis for stars fainter than magnitude 9.5. Otherwise the scale and color system remain unchanged. With these minor revisions included, the corrections for the six catalogues are as in Table VII. The consistency of the results is illustrated by Table VIII. The corrections for Greenwich and Yerkes were independently determined with the aid of HPP, the results (Tables IX-XIV) confirming those of Table VII