Brief communication: Precision measurement of the index of refraction of deep glacial ice at radio frequencies at Summit Station, Greenland

We report on the measurement of the index of refraction of glacial ice at radio frequencies at Summit Station, Greenland. This measurement is of particular importance for the Radio Neutrino Observatory Greenland, an experiment currently under construction at Summit Station that seeks to detect radio signals from ultra-high-energy neutrino interactions in the ice. By correlating radio reflections in the bulk ice with features in the conductivity measurements from ice cores, we determine the index of refraction as n = 1.778 ± 0.006.