The ability to point back to the detected sources is critical in a neutrino telescope. In order to get the best possible angular resolution a good positioning and time calibration are required. The absolute time resolution (fix a specific time for each neutrino event w.r.t. UT) depends on Time offsets and Electronic paths (Electro-optical cable between the junction box and the shore station). In order to obtain correlations with the physics phenomena (e.g. GRB) an accuracy of ~1 ms is required in the absolute timing. Relative timing resolution (among OMs) depends on Transit time spread (TTS) of the PMTs, Optical properties of the sea water (light scattering and chromatic dispersion (1.5 ns)) and Electronics (s < 0.5 ns). In order to get the best angular accuracy (i.e. only limited by reconstruction) the relative time uncertainty coming from the electronics must be < 0.5 ns.
