The 1.3m has been removed from the CTIO exposure time calculator. The values obtained using this calculator were found to be too optimistic by several orders of magnitude. Please estimate you exposure times using the values found at the ANDICAM detector website (http://www.astronomy.ohio-state.edu/ANDICAM/detectors.html#sens [1]).
Links
[1] http://www.astronomy.ohio-state.edu/ANDICAM/detectors.html#sens