We report a study of the three-dimensional ( 3D ) outflow structure of a 15 \arcsec \times 13 \arcsec area around H _ { 2 } peak 1 in Orion KL with slit-scan observations ( 13 slits ) using the Immersion Grating Infrared Spectrograph .
The datacubes , with high velocity-resolution ( \sim 7.5 km s ^ { -1 } ) provide high contrast imaging within ultra-narrow bands , and enable the detection of the main stream of the previously reported H _ { 2 } outflow fingers .
We identified 31 distinct fingers in H _ { 2 } 1 - 0 S ( 1 ) \lambda 2.122 \micron emission .
The line profile at each finger shows multiple-velocity peaks with a strong low-velocity component around the systemic velocity at { V _ { LSR } } = + 8 km s ^ { -1 } and high velocity emission ( | { V _ { LSR } } | = 45 - 135 km s ^ { -1 } ) indicating a typical bow-shock .
The observed radial velocity gradients of \sim 4 km s ^ { -1 } arcsec ^ { -1 } agree well with the velocities inferred from large-scale proper motions , where the projected motion is proportional to distance from a common origin .
We construct a conceptual 3D map of the fingers with the estimated inclination angles of 57 ^ { \circ } - 74 ^ { \circ } .
The extinction difference ( \Delta A _ { v } > 10 mag ) between blueshifted and redshifted fingers indicates high internal extinction .
The extinction , the overall angular spread and scale of the flow argue for an ambient medium with very high density ( 10 ^ { 5 } - 10 ^ { 6 } cm ^ { -3 } ) , consistent with molecular line observations of the OMC core .
The radial velocity gradients and the 3D distributions of the fingers together support the hypothesis of simultaneous , radial explosion of the Orion KL outflow .