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.
Resolution	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
Detector	Spectrograph - HgCdTe, 2024 x 2048 (Hawaii 2RG) Slit viewer - HgCdTe, 1024 x 1024 (Hawaii 1) Operating temperature approximately 77° K
Detector electronics	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 <5 electrons for MCDS with 16 reads
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.
Cooling	Liquid nitrogen held in instrument; minimum hold time 1 day, goal ~ 3+ days.
Size & Weight	Approximately 50 inches long and 800 lbs.