A Possible Optical Counterpart for the Triple Pulsar System PSR B1620-26

We have searched deep optical images of the globular cluster M4 for a possible optical counterpart for the third body in the PSR B1620-26 system. We identify as a possible optical counterpart a star located within ${0.3}^{\mathrm{\prime }\mathrm{\prime }}$ of the nominal pulsar position with $V\approx 20$. This magnitude is consistent with a main sequence cluster member with $M\approx 0.45M_{\odot }$. However, this star may be blended with fainter stars, and the probability of a chance superposition is non-negligible.