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Description
This catalog contains positions, precessions, proper motions, and photographic magnitudes for 20,554 stars. These were derived from photographs taken at the Royal Observatory, Cape of Good Hope between 1923 and 1928. It covers the astrographic zones -40 degrees to -52 degrees of declination. The positions are given for epoch 1900 (1900.0). It includes spectral types for many of the stars listed. It extends the earlier catalogs derived from the same plates to fainter magnitudes. The computer-readable version consists of a single data table. The stated probable error for the star positions is 0.024 seconds of time (R.A.) and 0.25 seconds of arc (Dec.) for stars with one determination, 0.017 seconds of time, and 0.18 seconds of arc for two determinations, and 0.014 / 0.15 for stars with three determinations. The precession and secular variations were derived from Newcomb's constants. The authors quote probable errors of the proper motions in both coordinates of 0.008 seconds of arc for stars with one determination, 0.0055 seconds for stars with two determinations, and 0.0044 for stars with three. The photographic magnitudes were derived from the measured diameters on the photographic plates and from the magnitudes given in the Cape Photographic Durchmusterung. The spectral classification of the catalogued stars was done with the assistance of Annie Jump Cannon of the Harvard College Observatory. The user should consult the source reference for more details of the measurements and reductions. See also the notes in this document for additional information on the interpretation of the entries.
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