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Detailed studies of the ages and star formation histories of the most distant known galaxies promise to provide new insight into the epoch when the first sources emerged from the cosmic dark ages as well as the practicality of using JWST to search for their progenitors. Recent progress analysing the spectral energy distributions of two spectroscopically-confirmed z>9 galaxies comma MACS1149_JD1and GNz-11 comma has been particularly informative. One surprise is the remarkable brightness of GNz-11 at z=11 which suggests that luminous sources may somehow emerge very promptly. Until now comma GNz-11 has been regarded as an anomaly. Here we propose to obtain WFC3-G141 grism spectroscopy for a second luminous candidate thought to be at zvirgul10.9 comma XMM3-3085 with MUV=-23.7 mag. Both sources are consistent with being drawn from the bright end of UV luminosity function at z=5-10. However comma as was the case for GNz-11 comma without a spectroscopic redshift a low redshift interloper or a faint dwarf star cannot be excluded. A suitable spectrum for XMM3-3085 cannot be secured with ground-based instruments because of the low atmospheric transparency at the expected wavelength of its Lyman break. Confirmation of the redshift of XMM3-3085 can be economically secured with HST and would strengthen the evidence supporting the emergence of luminous galaxies at z=11 comma only 400 Myrs after the Big Bang. This would provide a major impetus for surveys for earlier galaxies with JWST.