A stroboscope designed to observe pulsars in the optical spectrum is presented. The absolute phase of the stroboscope is synchronized to better than 2.5 microseconds with the known radio ephemerides for a given pulsar. The absolute timing is provided by the GPS clock. With such a device phase resolved photometry of pulsars can be performed. We demonstrate the instruments capabilities with the results of a set of observations of the Crab pulsar, the brightest of the known optical pulsars, with a visual magnitude of 16.5, and a rotational frequency of ~29Hz.
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