2014MNRAS.443.3118S

We present rest-frame optical and near-infrared detections of one of the highest redshift submm-selected galaxies to date, HDF850.1. We do not detect the previously proposed counterpart HDF850.1K in new deep J- and H-band Hubble Space Telescope Wide Field Camera 3 data, placing a strong limit of H - K > 3.8, concluding that the K-band source is spurious. However, we detect 5.8and 8µm emission co-located with the submm in deblended images. After modelling and removing the flux contributions from another foreground galaxy, we constrain the stellar mass of HDF850.1 to be (2.5±1)µ-1x10¹¹M_☉ for a lensing magnification µ = 1.9±0.3, with a specific star formation rate of 8.5 G/yr, faster than the 1-4 G/yr observed for UV-selected galaxies at this epoch.