Quick Reference |
Location | Forward Cassegrain module, Keck I;
shares module with NIRC |
Secondary mirror | f/25, gold-coated |
Dewar orientation | ``Uplooker'' dewar (no tertiary mirror) |
Dewar hold time | ~24 hr (LHe dewar)
>30 hr (LN dewar) |
Rotator | 540° rotation |
Guiding system | One visible-wavelength offset guider available; 61×46 arcsec FOV |
Scale at detector | 0.0011 arcsec/µm; 0.0847 arcsec/75 µm px |
Detector type | Boeing Si:As moderate-flux array |
Detector format | 128×128 px (75 µm px) |
Data format | 6-dimensional fits file (see figure):
[X,Y,chpbeams,savesets,nodbeams,nodsets] |
Flexure | <0.2 arcsec (<3 px) during 3 hour transit near zenith |
Apertures | 2 longslits, occulting disk, ``clear'' (imaging) |
Dispersive elements | 1 low- and 1 moderate-resolution grating |
Imaging option | Dispersive elements removed from light path |
Filters | 16 slots; 14 filters provided |
User filters | Not available |
Collimator focal length | 324 mm |
Camera focal length | 230 mm |
Pupil size | 13 mm |
Field of view | 10.84×10.84 arcsec | ||||||||||||||||||||||||||||||||
Detector pixel scale | 0.0847 arcsec/px (75 µm/px) | ||||||||||||||||||||||||||||||||
Wavelength range (imaging) | 3.5-25 µm | ||||||||||||||||||||||||||||||||
Standard filters |
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Image size at 10 µm | 0.25 arcsec FWHM (instantaneous)
0.30 - 0.35 arcsec FWHM ( typical for longer integrations) |
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Expected count rate | 11,000 ADU/Jy·sec at 11.7 µm filter from sky | ||||||||||||||||||||||||||||||||
Sensitivity to faint stellar objects 2 | 17mJy 2 at 11.75 µm
(SiC filter)
100 mJy at 17.65 µm (17.65 filter) |
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Mode changes | 2 min changeover between imaging and spectroscopy |
Total slit length | 10.24 arcsec |
Usable slit length¹ | 7.0 arcsec |
Detector scale | 0.080 arcsec per px (75 µm px) |
Wavelength range (spectra) | 3.5-25 µm |
Order blocking filters | N wide (8.1-13.0 µm)
Spec 20 (>13.71 µm long pass) |
Slit widths | 3 pix, 6 pix, and 12 pix wide |
Current gratings | 8 g/mm (10.0 µm blaze); R=100
50 g/mm (19.5 µm blaze); R=1400 |
Number of grating slots | 2 slots available, both used |
Corresponding dispersions | LRES: 0.037 µm/px;
HRES: 0.0024 µm/px (10 µm, N=2) HRES: 0.0048 µm/px (20 µm, N=1) |
Spectral coverage, single exposure (128 px) | LRES: 4.7 µm
HRES (@10.0µm): 0.31 µm HRES (@20.0µm): 0.62 µm |
FWHM resolution | R=100 and R=1400 (3 px slit) |
Count rate at 10µm | TBD |
Sensitivity to faint stellar objects² | 150 mJy |