Sentence:  The antenna patterns and the power gain at the peak of the beam were both measured ( Mayer , McCullough , and Sloanaker , 1958 b ) , so that the absolute <WSD>power</WSD> sensitivity of the antenna beam over the solid angle of the moon was known . 
Meaning of the word marked with <WSD> tags:  (physics) the rate of doing work; measured in watts (= joules/second)