We report optical B-band observations with the Large Binocular Telescope (LBT) of the isolated neutron star RBS1774. The stacked image with a total exposure of $2\fh5$ reveals a candidate optical counterpart at m B = 26.96 ± 0.20 at position $\alpha {\rm (2000)} = {\rm 21^h43^m03\fs40}$, $\delta{\rm (2000)} = +06\degr54^\prime17\farcs5$, within the joint Chandra and XMM-Newton error circles. We analyse archival XMM-Newton observations and derive revised spectral and positional parameters. The predicted optical flux from the extrapolated X-ray spectrum is likely twice as high as reported before. The measured optical flux exceeds the extrapolated X-ray spectral flux by a factor ${\sim}40$ (15-60 at 1 σ confidence). We interpret our detection and the spectral energy distribution as further evidence of a temperature structure over the neutron star's surface and present a pure thermal model reflecting both the SED and the pulsed fraction of the light curve.
