Optical spectra of U Sco during days 4.81–9.83 after outburst maximum. The time since estimated maximum and emission line identifications are marked. Note the changes in the line profile, and the decrease in the strength of the oxygen and nitrogen lines by day ~7. For clarity, the zero level of the spectra of days 4.805, 5.806, 6.826, 7.827 and 8.826 are offset, respectively, by a constant value of 1.6, 1.3, 1.0, 0.7 and 0.3 in flux units.