Assertion: star's distance | /r/HasProperty | given by pd
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Source sentences:
text: Alternatively, sometimes the polar distance ( PD ) is used, which is given by PD = 90 deg - Dec ; the most prominent reference known to the present author using PD instead of Dec is John Herschel's General Catalogue of Non-stellar Objects (GC) of 1864, but this (equivalent) alternative has come more and more out of use since, so that virtually all current astronomical databases use Dec .