NIRSPEC - the Near InfRared echelle SPECtrograph

Principal Investigator: Ian McLean (UCLA)

The Design and Development of NIRSPEC: A Near-Infrared Echelle Spectrograph for the Keck II Telescope, Ian S. McLean et al., SPIE vol. 3354, pp. 566-578.

The Near Infrared Spectrometer (NIRSPEC), a cryogenic cross-dispersed echelle spectrograph, features spectroscopy over the 0.96-5.5 micron range at resolutions of R=2000 or 25,000. The slit-viewing camera provides additional capability to image fields in a 46"-square field from 1-2.5 microns. The software interface includes planning tools for users to prepare observational setups and exposure sequences.

Detector Characteristics

Slit-viewing Camera (SCAM)
Detector Rockwell HgCdTe 256x256
Plate Scale 0.18"/pixel
Gain 5 e-/ADU
Read Noise 10 e-
Linear Limit 120,000 e- (30,000 ADU)
Field of View 46" square field
Wavelength Sensitivity 0.95 - 2.5 microns
SCAM detector layout low resolution diagram
high resolution diagram

Spectrograph (SPEC)
Detector ALADDIN-3 InSb 1024x1024, 27 micron pixels
Gain 5.8 e-/ADU
plot of historical gain values
Read Noise 23 e-
plot of historical read noise values
Dark Current 0.8 e-/s/pixel
plot of historical dark current values
Linear Limit 90,000 e- (15,500 ADU)
Charge Persistence >4,000 ADU/co-add
Wavelength Sensitivity 0.95 - 5.5 microns
SPEC detector layout low resolution diagram
high resolution diagram

Filter Complement

N. B.: there is now an AO pupil stop in both filter wheels so all filters can be accessed behind AO.

Filter Wheel No. 1

L-Prime 3.420-4.120

M-Prime 4.570-4.810

KL 2.134-4.228

HeI 1.078-1.088

Pa-Beta 1.276-1.289

H2 2.110-2.129

FeII 1.639-1.654

M-Wide 4.420-5.530

Filter Wheel No. 2

Nirspec-1 0.947-1.121

Nirspec-2 1.089-1.293

Nirspec-3 (J) 1.143-1.375

Nirspec-4 1.241-1.593

Nirspec-5 (H) 1.413-1.808

Nirspec-6 1.558-2.315

Nirspec-7 1.839-2.630

CO 2.282-2.305

K 1.996-2.382

K-Prime 1.950-2.295

Basic NIRSPEC Specifications

Location RNAS, Keck-2, f/15 input beam
Spectroscopy: Low resolution: R=2000 (150 km/s), 2-pixel slit (0.38")
High resolution: R=25,000, 3-pixel slit (0.43")
Low-Res Slits: 42x0.380" (2-pix)
42x0.570" (3-pix)
42x0.760" (4-pix)
High-Res Slits: 0.144"x12 (1-pix)
0.288"x12 (2-pix)
0.432"x12 (3-pix)
0.576"x12 (4-pix)
0.720"x12 (5-pix)
0.288"x24 (2-pix)
0.432"x24 (3-pix)
0.720"x24 (5-pix)
Guider: 1024x1024 MAGIQ, 0.20 arcsec pixels, annular FOV. Filters: V, R, I, RG780, ND: Open, ND1, ND2, ND3, ND4
Guiding also available on SCAM.
Optics: Spectrograph optics all reflecting, diamond-machined, post-polished, Al/Ni-Al substrates, silver or gold coated.
Cryogenics: Full vacuum enclosure, CCR continuous cooling to 60 K (30 K for the ALADDIN).
All cryogenic mechanisms, including image derotator to fix sky PA on slit.
Electronics: Transputer-based architecture.
User Interface: DataViews (control) and IDL (quicklook, image rotator control, and echelle format simulator).
Performance: SCAM image quality FWHM 0.3-0.55" typical.
SCAM J-band zero point: 24.7 mag @ 1 DN/s.
Other sensitivity TBD.

Additional Information

Web & Contact
WWW sites: NIRSPEC Home Page
CARA contact: