SNR as a function of  observation time and intrinsic (unlensed) HI mass. We assume the HI line is a boxcar function of width 500 kHz (\(\sim250\ \mathrm{kms}^{-1}\) width) observed with the equivalent channel width and at a magnification of 105. All values of SNR < 5 have been blanked and the color scale saturates at SNR = 100. The solid and dashed line represent the mean and the lower \(2\sigma\) HI mass estimates respectively. The estimate was made using the mean and RMS stellar masses from the original SLACS sample  (Newton et al, 2011), converted to HI using the Maddox et al. (2015) \(M_{HI\ }-M_{\star}\) galaxy relation.