We generalize the technique of to map dust column density through a molecular cloud ( Nice ) to an optimized multi-band technique ( Nicer ) that can be applied to any multi-band survey of molecular clouds .
We present a first application to a \sim 625 \mbox { deg } ^ { 2 } subset of the Two Micron All Sky Survey ( 2MASS ) data and show that when compared to Nice , the optimized Nicer technique ( i ) achieves the same extinction peak values , ( ii ) improves the noise variance of the map by a factor of 2 and ( iii ) is able to reach 3 \sigma dust extinction measurements as low as A _ { V } \simeq 0.5 \mbox { magnitudes } , better than or equivalent to classical optical star count techniques and below the threshold column density for the formation of CO , the brightest \mbox { H } _ { 2 } tracer in radio-spectroscopy techniques .
The application of the Nicer techniques to near-infrared data obtained with a 8 meter-class telescope with a state-of-the-art NIR camera , such as the VLT-ISAAC combination , will be able to achieve dynamic ranges from below 10 ^ { 21 } \mbox { protons cm } ^ { -2 } to over 10 ^ { 23 } \mbox { protons cm } ^ { -2 } ( A _ { V } in the range [ 0.3 , 60 ] ) and spatial resolutions < 10 ^ { \prime \prime } , making use of a single and straightforward column density tracer , extinction by interstellar dust .