Here are the latest specifications on NIRES. They will be updated as information becomes available when the instrument is commissioned.
|Location||Right Bent Cassegrain (RBC) port on Keck 2|
|Input f/ ratio||f/15 nominal (f/16.6 cold circular pupil mask to inscribe Keck entrance pupil)|
|Wavelength range and Resolution||
Fixed configuration, simultaneous J, H and K band spectra in five orders from 0.94 to 2.45 µ. Orders 3 through 7 with overlap, the only gap is between 1.85 - 1.88 µm, a region of poor atmospheric transmission.
The mean resolution is 2700. As expected the resolution changes with order and wavelength.
|Field of view||Slit viewer: 2.1 x 2.1 arcmin (K' only)
Optical guider: 1.8 x 1.8 arcmin
|Guiding||The main guider for NIRES is an off-axis visual guider. The K band slit-viewing camera can be used as a backup guider.|
|Pixel scale||Slit viewer: 0.123 arcsec/pixel. Spectrometer: 0.15 arcsec/pixel|
|Filters||K' only for slit viewing camera|
|Slit||Fixed 0.55” by 18”|
|Sensitivity||Please see the sensitivity section|
|Minimum frame time||1.48 seconds for the H2RG|
Spectrograph - HgCdTe, 2024 x 2048 (Hawaii 2RG)
SDSU-III, mounted near instrument, fiber connection to a target computer (Sun), similar to OSIRIS detector server.
|H2RG Read noise||
15 electrons per CDS read
|H2RG Dark current||Internal background of 0.13 electrons/pixel/sec|
|H2RG Gain||3.8 e-/ADU|
|H2RG Well depth||150000 electrons|
|H2RG Persistence||Significant persistence is present for some 10 minutes if the maximum ADUs are above 4000.|
|Construction||Self-contained instrument with no moving parts except for the active flexure correction system; vacuum dewar, liquid nitrogen cooled with an internal cryogen tank.|
Liquid nitrogen held in instrument; minimum hold time 1 day, goal ~ 3+ days.
|Size & Weight||Approximately 50 inches long and 800 lbs.|
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