Pulsars with compact companions in close eccentric orbits are unique laboratories for testing general relativity and alternative theories of gravity .
Moreover , they are excellent targets for future gravitational wave experiments like LISA and they are also highly important for understanding the equation of state of super-dense matter and the evolution of massive binaries .
Here we report on optical observations of the 1.02 M _ { \odot } companion to the pulsar PSR J1141 - 6545 .
We detect an optical counterpart with apparent magnitudes V = 25.08 ( 11 ) and R = 24.38 ( 14 ) , consistent with the timing position of the pulsar .
We demonstrate that our results are in agreement with a white dwarf companion .
However the latter is redder than expected and the inferred values are not consistent with the theoretical cooling tracks , preventing us from deriving the exact age .
Our results confirm the importance of the PSR J1141 - 6545 system for gravitational experiments .