HITS
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HITS

High Resolution Ionosphere and Thermosphere Spectrograph

HITS optical layout.

Design Features

Summary
f/5.4 1-m Rowland circle in-plane Eagle design spectrograph with 1/8 m telescope
EUV/FUV (50-180 nm) coverage
Selectable 150 nm passband
0.05-0.07 nm spectral resolution
Telescope
Off-axis parabola (2.5 cm X 3.1 cm)
125 mm focal length
SiC reflective coatting
Grating
Toroidal surface with 995 and 1000 mm focii 
6061-T6 Al alloy blank (22 cm X 13 cm)
3600 lines/mm tripartite ruled grating
Blazed for 120 nm
Focus achieved by moving the grating
SiC reflective coating
Detector
Windowless, with clamshell vacuum door mechanism
CsI photocathode
40 mm diameter microchannel plate z-stack
wedge & strip anode
1024 dispersion axis pixels
Field-of-view
0.06-degree vertical resolution (3 km)
4.6-degree horizontal field-of-view (230 km)
Co-aligned with ISAAC and LORAAS
Limb scanned by gimballing the main platform

First HITS spectrum, spectral resolution 0.12 nm (not quite focused).HITS_tempmod_fit.gif (3943 bytes)

Scientific Features

Focused studies of airglow and auroral processes
Daytime electron densities from O II 83.4 nm multiple
Daytime neutral densities and temperatures from molecular bands
Nighttime electron densities and temperatures from OI 91.1 nm recombination continuum
Dopper-shifted signatures from charge-exchanged auroral ions