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IMACS Specs

IMACS Optical Specifications

 Long Camera Mode

Focal Length 641.8 mm
Focal Ratio f/4.3 (imaging), f/2.66 (anamorphic)
Field of View 15.46 arcmin x 15.46 arcmin, Square
Vignetting None
Total Detector Area 239 arcmin²
Pixel Scale 9.0 pixels/arcsec
Design Wavelength Range 0.365 µm - 1.0 µm
Allowed Wavelength Range 0.34 µm - 1.1 µm

 

Short Camera Mode

Focal Length 355.6 mm
Focal Ratio f/2.38 (imaging), f/1.47 (anamorphic)
Field of View 27.20 arcmin x 27.20 arcmin, Radiused at 36.4 arcmin
Total Detector Area (direct imaging) 635 arcmin²
Total Detector Area (spectroscopy) 737 arcmin²
Pixel Scale 5.0 pixels/arcsec
Design Wavelength Range 0.39 µm - 1.05 µm
Allowed Wavelength Range 0.39 µm - 1.1 µm

 

Current Long Camera Gratings

Ruling Density Blaze Angle Order Central Wavelength Wavelength Range Dispersion Dispersion
Lines/mm Degrees   µm µm R/0.5-arcsec slit A/pixel
300.0 4.3 1 0.665 0.365 - 0.974 2162 0.743
600.0 8.63 1 0.518 0.365 - 0.675 3491 0.378
600.0 13.0 1 0.841 0.684 - 1.000 6117 0.387
1200.0 17.45 1 0.444 0.365 - 0.523 6542 0.194
1200.0 26.7 1 0.924 0.846 - 1.000 20693 0.188
1200.0 26.7 2 0.404 0.365 - 0.443 15740 0.096
1200.0 26.7 2 0.520 (max) 0.482 - 0.557 28082 0.092
300.0 36.87 11 0.336 0.308 - 0.364 20687 0.068
300.0 36.87 10 0.369 0.338 - 0.399 20687 0.074
300.0 36.87 9 0.410 0.375 - 0.444 20687 0.084
300.0 36.87 8 0.461 0.422 - 0.499 20687 0.094
300.0 36.87 7 0.527 0.483 - 0.571 20687 0.107
300.0 36.87 6 0.615 0.563 - 0.666 20687 0.126
300.0 36.87 5 0.738 0.676 - 0.799 20687 0.150
300.0 36.87 4 (pointless) 0.922 0.845 - 0.998 20687 0.187

 

Short Camera Grisms

200.0 15.0 1 0.66 0.39 - 1.0 ? 2.037
300.0 17.5 1 0.67 0.39 - 1.0 ? 1.341
600.0 34.0 1 0.77 0.56 - 1.0 ? 0.583
600.0 34.0 2 0.39 0.39 - 0.52 ? 0.291

 

Notes:

A 1200/36.8 grating exists from Richardson Grating Laboratory.
The 600 l/mm grism uses a very heavy lead glass. Transmission in the blue in second order is very poor.
Here is a web page which computes Long Camera grating angles.

 

Initial Filter Complement

Filters are 165 mm x 165 mm square, 12 mm thick (nominal). The filter frames can be modified to allow larger filters, while smaller filters may require an adaptor (most likely a cutout from a 1/2" aluminum plate). Click here for more complete filter specifications.

Clear Spectroscopy Filters for both cameras
Johnson/Cousins/Bessell BVRI. I-band has a red cutoff to match that used by Landolt at CTIO.
There are some plans for a third party to purchase a refelctive U-band filter for the f/4 camera.
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