To achieve better linear resolution, two of the closest regions in the GAS DR1 are selected for this study.  L1688 in Ophiuchus sits at a distance of 137.3 pc \citep{2017ApJ...834..141O}, and B18 in Taurus sits at a distance of 135 pc \citep{2014ApJ...786...29S}.  The GBT FWHM beam size at 23 GHz is 36″, corresponding to ~4350 AU (~0.02 pc) at these distances.  The GBT beam size at 23 GHz also matches well with the Herschel SPIRE 500 μm FWHM beam size of 32″, avoiding complications involving convolution/deconvolution when we compare the two maps (see §\ref{839022} and discussions in \citealp{Friesen2017}).