Work clock
As a working clock was in the classical Astrometrie (measurement of Sternörtern, location determination, etc.) refers to that watch, on the visual observer or measurement assistants, the time points of the measured rating passages discovered. Before and after the observations, it was compared with the so-called master clock ( chronometer , pendulum or quartz clock ), which in turn - if available - was connected to an even more precise signal ( telegraphy , clock transport, international time signal transmitter ) by means of a time comparison .
As long as good clocks were still expensive and sensitive, robust timekeepers or stopwatches that often had to be connected to the master clock were used when traveling (on expeditions , in nautical science or in astrogeodesy ) . On Observatories which was used until the early 20th century most eye-ear method with a precision pendulum clock whose ticking around the observatory dome could be heard. As a result, the accuracy reached almost hundredths of a second, and there was no need for your own work clocks. From about 1920 came trailing pointer -Chronometer and writing chronographs on the market, which experienced observers could also stop short consecutive times.
With the first portable quartz clocks , the traditional work clock was often superfluous, especially when using writing or printing chronographs . The measurements became even easier with the advent of digital stopwatches around 1975, which could mostly take over the function of work and master clock.
Today, visual observations have largely been replaced by electro-optical processes that can even work directly in the international UTC time system .