The optical counterpart of the isolated neutron star RX J1605.3+3249

We have detected the optical counterpart to the nearby isolated neutron star RX J1605.3 + 3249 using observations from the Space Telescope Imaging Spectrometer aboard the Hubble Space Telescope. The counterpart, with m(50CCD) = 26.84 +/- 0.07 mag and very blue colors, lies close to the ROSAT HRI error circle and within the Chandra error circle. The spectrum is consistent with a Rayleigh- Jeans tail whose emission is a factor of approximate to14 above the extrapolation of the X-ray blackbody, and the source has an unabsorbed X-ray-to-optical flux ratio of log (f(X)/F-opt) = 4.4, similar to that of other isolated neutron stars. This confirms the classification of RX J1605.3 + 3249 as a neutron star.