Signal To Noise Ratio

Using data referring to UVES, if the seeing is 0.8 arcsec, for U band, we get n_bin=n_pix=6, RON= 4.4  e^- and $DARK=1 ~e^{-}\slash pix\slash h$ and with data referring to the Table 2.6 and 2.7 we found:

To be matched with the value found by the ETC of 8.