About binary pair stars (Binary Pulsars):
Such phenomena is caused by the occurrence of refraction and aberration of starlight.
“A test of general relativity from the three-dimensional orbital geometry of a binary pulsar Binary pulsars provide an excellent system for testing general relativity because of their intrinsic rotational stability and the precision with which radio observations can be used to determine their orbital dynamics. Measurements of the rate of orbital decay of two pulsars have been shown1, 2 to be consistent with the emission of gravitational waves as predicted by general relativity, but independent verification was not possible. Such verification can in principle be obtained by determining the orbital inclination in a binary pulsar system using only classical geometrical constraints. This would permit a measurement of the expected retardation of the pulse signal arising from the general relativistic curvature of space-time in the vicinity of the companion object (the ‘Shapiro delay’). Here we report high-precision radio observations of the binary millisecond pulsar PSR J0437–4715, which establish the three-dimensional structure of its orbit. We see the Shapiro delay predicted by general relativity, and we determine the mass of the neutron star and its white dwarf companion. The determination of such masses is necessary in order to understand the origin and evolution of neutron stars3.”
Unfortunately, Shapiro experiments without taking into account the effect of Earth’s atmosphere. It’s not time dilation predicted by general relativity, but the effects of aberration of light to change with time. Radio telescope as an observer at the Earth should be taking into account the effect of layer of Earth’s atmosphere (refraction, aberration, density, and pressure).
Binary pulsars nothing to do with Einstein’s relativity.
An optical pulsar is a pulsar which can be detected in the visible spectrum.
“A Pulsar Discovery: First Optical Pulsar.” Moments of Discovery, American Institute of Physics, 2007 (Includes audio and teachers guides).