The isolated neutron star RBS1774 revisited. Revised XMM-Newton X-ray
  parameters and an optical counterpart from deep LBT-observations
  We report optical B-band observations with the Large Binocular Telescope LBT
of the isolated neutron star RBS1774. The stacked image with total exposure
2.5h reveals a candidate optical counterpart at mB = 26.96 +- 0.20 at position
RA(2000) = 21:43:03.4, DEC(2000)} = +06:54:17:5, 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 ~40 (15 - 60 at 1sigma 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.
